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ANILI N  E 

AND    ITS  DERIVATIVES. 


LONDON: 

PRINTED  BY  WILLIAM  CROOKES,  CHEMICAL  NEWS  OFFICE, 
BOY  COURT,  LUDGATE  HILL,  E.C. 


ON 


ANILINI 


AND    ITS  DERIVATIVES 


A  TREATISE  UPON  THE 


MANUFACTURE  OF  ANILINE  AND  ANILINE  COLOURS, 


M.    REIMANN,    P.D.,  L.A.M. 

TO  WHICH  IS  ADDED,  IN  AN  APPENDIX, 

"  The  Report  on  the  Colouring  Matters  derived  from  Coal  Tar,  Shown  at  the  French 
Exhibition,  1867."   By  Dr.  A.  W.  Hofmann,  F.R.S.,  MM.  G.  de  Laire,  and  Ch.  Givavd. 

THE  WHOLE  REVISED  AND  EDITED  BY 

WILLIAM    CROOKES,    F.R.S.,  &>c. 


JOHN    WILEY    AND  SON, 
CLINTON    HALL,    ASTOR  PLACE, 
NEW  YORK. 
1868. 


TP 
fit 


PREFACE. 


During  the  last  ten  years  the  manufacture  of  Aniline  and 
its  coloured  derivatives  has  grown  from  nothing  to  propor- 
tions never  dreamed  of  by  their  discoverers.  The  hitherto 
unattainable  brilliancy  of  these  colours  dazzled  the  public, 
and  their  popularity  increased  with  astonishing  rapidity. 
Simultaneously  with  the  progress  of  Aniline  industry, 
curiosity  was  naturally  awakened  as  to  the  manufacturing 
details  by  which  such  bright  colours  could  be  obtained 
from  coal. 

The  several  steps  of  the  Aniline  manufacture  have  fre- 
quently been  set  forth,  and  the  theories  by  which  chemists 
account  for  the  production  of  Aniline  and  the  colours  derived 
from  it  have  been  explained  on  several  occasions.  But  none 
of  these  accounts,  though  many  of  them  are  trustworthy, 
give  a  clear  representation  of  the  aCtual  state  of  the  manu- 
facture as  adopted^on  a  commercial  scale.  Nowhere  do  we 
find  a  plain  statement  of  the  methods  of  obtaining  aniline 
and  its  derivatives,  nor  a  description  of  the  apparatus 
actually  in  use  in  manufactories. 

The  Author  of  the  following  treatise  has  made  it  his  objeCt 
to  supply  this  want.  He  has  endeavoured  to  give  a  compre- 
hensive and  accurate  account  of  this  industry  as  it  is  carried 


vi 


PREFACE. 


on  at  the  present  time ;  he  has,  moreover,  given  the  previous 
methods  of  manufacture  in  an  historical  introduction,  and 
the  literature  of  the  subjeCt  down  to  the  most  recent  im- 
provements has  been  fully  laid  under  contribution. 

The  book  has  succeeded  so  well  in  Germany  that  the 
Author  has  been  induced  to  prepare  it  for  the  English  public. 
Whilst  translating  it  he  has  not  failed  to  incorporate  in  this 
English  edition  all  improvements  and  observations  made 
since  the  appearance  of  the  German  edition.  Several  new 
colouring  matters  recently  introduced  into  commerce  are 
described.  Theoretical  considerations  have  been  strictly 
limited  to  those  necessary  to  the  clear  understanding  of  the 
manufacturing  processes  spoken  of. 

As  the  sheets  of  Dr.  Reimann's  work  were  passing  through 
the  press,  the  very  complete  and  valuable  Report  by  Dr. 
Hofmann,  F.R.S.,  MM.  G.  de  Laire  and  Ch.  Girard,  "  On  the 
Colouring  Matters  derived  from  Coal  Tar,  shown  at  the  French 
Exhibition,  1867,"  appeared  in  the  Moniteur  Scientifique 
of  Dr.  Quesneville.  The  contents  of  this  were  seen  to  be 
of  such  importance  to  all  interested  in  the  Aniline  colour 
industry,  that  the  Editor  considered  it  advisable  to  translate, 
and  give  the  whole  Report  in  the  form  of  an  Appendix 
to  the  original  book.  A  more  appropriate  addition  to  Dr. 
Reimann's  work  could  not  well  be  imagined,  for  whilst 
the  Exhibition  Report  includes  several  novel  faCts  and 
recent  improvements  which  are  as  yet  known  to  few  but 
the  reporters  themselves,  Dr.  Reimann's  work  gives  that 
explicit  insight  into  the  theoretical  considerations  and 
manufacturing  operations  which  are  required  for  a  proper 
comprehension  of  this  important  branch  of  technical 
chemistry. 


INTRODUCTION 


Theoretical  Chemistry,  properly  so  called,  differs  from 
Practical  Chemistry  in  that  it  treats  of  all  existing  substances 
without  exception,  while  Practical  Chemistry  treats  only  of 
those  substances  the  production  of  which  is  capable  of 
yielding  a  material  advantage.  It  is  clear,  then,  that 
Practical  Chemistry  constitutes  only  a  part  of  Theoretical 
Chemistry. 

Since  Practical  Chemistry  becomes  capable  of  making 
new  observations  only  by  means  of  its  acquaintance  with 
faCts,  it  ought  to  make  public  its  observations ;  for  in  this 
way  only  is  it  possible  that  among  the  vast  number  of 
scientific  workers  who  thus  gain  additional  knowledge, 
some  particular  individual,  favoured  by  greater  gifts  or 
opportunities,  may  climb  to  a  yet  higher  step  of  the  great 
ladder.  Were  this  always  done  there  would  be  but  one 
chemical  science,  enriched  by  the  experiences  both  of  the 
modest  laboratory  and  of  the  great  manufactory. 

It  is  a  false  view  to  suppose  that  Theoretical  Chemistry 
occupies  itself  only  with  observations  made  on  a  small 
scale.  It  is  only  because  it  is  more  convenient  to  make 
observations  in  this  way  that  theoretical  chemists  employ 
small  quantities,  for  it  is  in  most  cases  indifferent  whether 


viii 


INTRODUCTION. 


the  reactions  are  effected  in  a  platinum  crucible  or  in  a 
reverbcraiar^T^nace.  In  some  cases,  however,  it  is  not 
unimportant ;  hence  it  would  be  foolish  always  to  expeCt 
the  same  result  from  the  crucible  as  from  the  furnace,  and 
a  well  trained  judgment  will  observe  the  difference  in  these 
particular  cases. 

Practical  Chemistry,  as  exemplified  in  chemical  manu- 
facture, must  always  be  in  advance  of  the  science,  because 
in  practice  so  much  attention  and  energy  is  brought  to 
bear  on  one  point  to  produce  a  given  result ;  it  is  the 
function  of  abstract  scientific  Chemistry  to  investigate  the 
progress  made,  and  to  correlate  the  new  observations  with 
those  previously  known.  Practical  Chemistry  can  only 
advance  by  paying  full  regard  to  theory,  and  Scientific 
Chemistry  can  only  progress  by  devoting  proper  attention 
to  practice. 

In  the  following  Treatise  I  have  endeavoured  always  to 
maintain  a  proper  relation  between  practice  and  theory. 
Regarding  the  former  as  the  pioneer  of  the  science,  I  have 
treated  in  the  first  place  of  the  purely  empirical  methods  of 
manufacture  discovered  by  aCtual  experience,  and  have  then 
proceeded  to  develope  theoretical  remarks. 

Where  theory  has  prepared  the  way  for  practice,  I 
naturally  give  theory  the  preference,  but  in  all  cases 
theoretical  speculations  have  been  limited  to  those  most 
important  and  really  useful  in  practice.  As  regards  the 
arrangement  of  the  Treatise  I  simply  follow  the  process  of 
manufacture. 

The  distillation  of  tar  has  been  passed  over  very  briefly, 
because  in  most  cases  it  is  not  effected  by  aniline  manu- 
facturers. The  proper  territory  of  aniline  production  is 
only  entered  with  the  manufacture  of  nitrobenzol. 

M.  REIMANN. 


CONTENTS. 


CHAPTER  I. 
BENZOL. 

PAGE. 


Properties  of  Benzol   i 

Produ&s  of  the  Distillation  of  Coal   2 

Light  Hydrocarbons               .  ■    3 

Apparatus  for  Distillation  of  Benzol   3 

Light  and  Heavy  Benzols   3 

CHAPTER  II. 

NITROBENZOL. 

Different  kinds  of  Commercial  Nitrobenzols   6 

Essence  of  Mirbane   7 

Apparatus  for  preparation  of  Nitrobenzol       ......  7-g 

Binitrobenzol   11 

Nitraniline   11 

CHAPTER  III. 
ANILINE. 

History  of  Aniline                                                                      .  12 

Preparation  of  Aniline  from  Nitrobenzol  14 

Apparatus  for  preparing  Aniline   15 

Other  Methods  of  preparing  Aniline   17 

Theoretical  Considerations  on  Aniline   18 

Properties  and  Reactions  of  Pure  Aniline   19 

Salts  of  Aniline   20 

Nitraniline   21 

Toluidine      ............  21 

Salts  of  Toluidine   22 

Chinoline     ......       *       ....  23 

Salts  of  Chinoline   23 


X  CONTENTS. 

~ t      •  PAGE. 

Odorine   24 

Paraniline   25 

Common  Aniline  Oil   25 

Commercial  Analysis  of  common  Aniline  Oil  for  Colour-producing 

Power   26 

Kuphaniline  and  Baraniline   27 

Apparatus  for  Testing  Aniline  Oil    28 

Poisonous  character  of  Aniline   31 

CHAPTER  IV. 
MAGENTA. 

Preparation  of  Magenta  from  Kuphaniline  and  Baraniline  ...  33 

Fuchsine   34 

Hofmann's  Process  for  preparing  Magenta  with  Bichloride  of  Carbon  34 
Reynard  and  Franc's  Process  for  preparing  Magenta  with  Bichloride 

of  Tin   35 

Brooman's  Process  for  preparing  Magenta   35 

Schlumberger's  Process  for  preparing  Magenta   36 

Perkin's  Process  for  preparing  Magenta  .       .       .       .       .       .       .  36 

Geber- Keller's  Process  for  preparing  Magenta  or  Azaleine         .       .  36 

Rubine   36 

Williams's  Process  for  preparing  Magenta   37 

Dale  and  Caro's  Process  for  preparing  Magenta     .....  37 

Depouilly  and  Lauth's  Process  for  preparing  Magenta       ...  38 

Hughes'  Process  for  preparing  Magenta   38 

Blackley  and  Watson's  Process  for  preparing  Magenta      .       .   *   .  38 

Medlock's  Process  for  preparing  Magenta      ,       .       .       .       .       .  39 

Girard  and  de  Laire's  Process  for  preparing  Magenta         ...  39 

Apparatus  used  for  preparing  Magenta   39 

Rosaniline   41 

Apparatus  for  Lixiviation  of  the  Crude  Magenta  mass    ....  43 

Smith's  Process  for  preparing  Magenta   45 

Gratrix's  Process  for  preparing  Magenta                                            .  45 

Furfurol  employed  by  Stenhouse  in  the  preparation  of  Magenta        .  46 

Fol's  Process  for  preparing  Magenta   46 

Koechlin's  Process  for  preparing  Magenta   46 

Smith's  Process  for  preparing  Magenta   47 

Delvaux's  Process  for  preparing  Magenta    ......  47 

Theoretical  Observations  on  Magenta   47 

Hofmann's  Researches  on  Rosaniline   4S 

Leukaniline  51 

Chrysaniline   53 

CHAPTER  V. 
ANILINE  BLUE  AND  VIOLET. 

Perkin  and^Church's  Process  for  preparing  Aniline  Violet  55 

Koechlin's  Process  for  preparinglAniline  Blue   56 

Hofmann's  Process  for  preparing  Aniline  Blue   56 


CONTENTS.  Xi 

PAGE. 

Bechamp's  Process  for  preparing  Aniline  Blue   56 

Crossley's  Process  for  preparing  Aniline  Purple  and  Yellow  ...  57 

Beale  and  Kirkham's  Process  for  preparing  Aniline  Violet  ...  57 

Phillips's  Process  for  preparing  Aniline  Violet   57 

Williams's  Process  for  preparing  Aniline  Blue  and  Violet  ...  58 

Price's  Process  for  preparing  Aniline  Blue  and  Violet    ....  58 

Dale  and  Caro's  Process  for  preparing  Aniline  Violet         ...  58 

Bleu  de  Paris  ,       .       ,       .  58 

SchsifTer  and  Gros-Renard's  Process  for  preparing  Aniline  Blue  .       .  58 

Bleu  de  Mulhouse   58 

Violet  de  Mulhouse                                                                 .       .  59 

Lauth's  Process  for  preparing  Aniline  Blue  and  Violet  ....  59 

Girard  and  De  Laire's  Process  for  preparing  Aniline  Blue  and  Violet  .  59 

Price's  Process  for  preparing  Aniline  Blue          .....  60 

Gilbee's  Process  for  preparing  Aniline  Blue     ......  61 

Schlumberger's  Process  for  preparing  Aniline  Blue   61 

Passavant's  Process  for  preparing  Aniline  Blue   61 

Night  Blue   61 

Bleu  de  Lyons   62 

Holliday's  Process  for8preparing  Aniline  Blue   62 

Williams's  Process  for  preparing  Aniline  Blue       .....  63 

Manufacture  of  Aniline  Blue  and  Violet,  as  actually  adopted      .       .  63 

Theoretical  considerations  on  Aniline  Blue  and  Violet   ....  66 

Triphenylrosaniline      ..........  67 

Mono-  and  Di-phenylrosaniline   68 

Perkin's  Violet,  Mauveine   68 

Theoretical  Researches  on  Mauveine   69 

Triethylrosaniline,  Hofmann's  Violet  .......  70 

Substitution  of  Methyl  for  Ethyl  in  Hofmann's  Violet  ....  72 

Substitution  Compounds  of  Aniline    .......  74 

Perkin's  Process  for  Preparing  Aniline  Violet  by  means  of  Brominated 

Oil  of  Turpentine    ..........  76 

CHAPTER  VI. 
ANILINE  GREEN. 

Lowe,  Calvert,  and  Cliffs  Process  for  preparing  Aniline  Green        .  77 

Miiller  and  Co.'s  Process  for  preparing  Aniline  Green   ....  78 

Use  of  Aldehyd  in  preparing  Aniline  Green                      ,  79 

Preparation  of  Aldehyd   80 

Argentine     ............  81 

Emeraldine,  Viridine,  or  Aldehyd  Green   81 

Lucius's  Process  for  preparing  Aniline  Green   81 

Usebe's  Process  for  preparing  Aniline  Green   82 

Aniline  Green  produced  in  the  manufacture  of  Hofmann's  Violet       .  82 

CHAPTER  VII. 
ANILINE  BLACK. 

Lightfoot's  Process  for  Preparing  Aniline  Black   84 

Kappelin  on  Aniline  Black   85 


xii  CONTENTS. 

PAGE. 

Koechlin's  Modifications  in  Printing  in  Aniline  Black  ....  85 
Cordillot's  Improvements  in  Printing  in  Aniline  Black       ...  85 

Lauth's  Process  for  preparing  Aniline  Black  86 

Hughes's  Process  for  preparing  Aniline  Black    .....  87 

CHAPTER  VIII. 
ANILINE  YELLOW. 

Picric  Acid,  Properties  and  Salts  of       .......  89 

Chrysaniline,  Victoria  Orange   go 

Vogel's  Process  for  preparing  Aniline  Yellow   go 

Zinaline   91 

Schiff's  Process  for  preparing  Aniline  Yellow       .....  gi 

Martin's  Process  for  preparing  a  Yellow  Dye  from  Naphthaline     .       .  gi 

CHAPTER  IX. 
ANILINE  BROWN. 

Havanna  Brown   g2 

De  Laire's  Process  for  preparing  Aniline  Brown   g2 

Kcechlin's  Process  for  preparing  Brown  from  Leukaniline  ...  93 

Decolorising  Aniline  Dyes   g4 

CHAPTER  X. 

TINCTORIAL   POWER   OF  ANILINE  COLOURS. 

Determination  of  the  amount  of  Colour  requisite  to  dye  a  certain 

weight  of  Wool  of  a  given  shade  .......  g$ 

Determination  of  the  amount  of  Wool  dyed  of  a  certain  colour  by  a 

given  weight  of  Colouring  matter  g6 

To  Distinguish  Aniline  Colours  from  one  another,  and  from  similar 

Colours  when  on  the  Textile  Fibre   gy 

Table  showing  the  Reactions  of  the  different  Colours  with  reagents       .  98 


APPENDIX. 

REPORT  ON  THE  COLOURING  MATTERS  DERIVED  FROM 

COAL  TAR, 

Shown  at  the  French  Exhibition,  1867.  By  Dr.  A.  W.  Hofmann,  F.R.S., 


MM.  G.  De  Laire,  and  Ch.  Girard   99 

Introduction   gg 

Coal  Tar  Dyes  exhibited  in  1862  ........  103 

Coal  Tar  Dyes  exhibited  in  1867    ........  103 

Industrial  processes  for  the  manufacture  of  Colouring  Matters  .       .  106 

Raw  Materials,  Benzol,  Toluol   106 

Nitrobenzol   106 

Aniline  •   no 

Diphenylamine   xii 


CONTENTS.  xiii 

PAGE. 

Rosaniline  and  its  Derivatives. — Manufa&ure  of  Rosaniline  and  its  Salts  112 

Preparation  of  the  crude  material   114 

Treatment  in  the  wet  way       .  h  .       ;       .       .  .115 

Crystallisation   116 

Preparation  of  Rosaniline   117 

Acetate  of  Rosaniline   118 

Chrysaniline. — Treatment  of  the  residues       ......  120 

Treatment  of  the  mother  liquors. — Regeneration  of  the  Arsenic  Acid  122 
Colouring  Matters  derived  from  Rosaniline. — Blue  and  Violet  colours 

obtained  by  Phenylation   123 

Phenylation  of  Rosaniline   125 

Diredl  Blue. — Purified  Blue   126 

Night  Blue   127 

Soluble  Blue. — Phenylic  Violets   128 

Violet  substances  obtained  by  Methylation  and  Ethylation     .       .       .  129 

Aniline  Green. — Aldehyd  Green   133 

Iodide  of  Ethyl  Green   136 

Substitution  Derivatives  of  Aniline. — Mauveine  and  its  Derivatives. — 

Aniline  Maroon  and  Brown   137 

Aniline  Black   138 

Derivatives  of  Phenol. — Carbolic  Acid      ."            .       .       .       .  144 

Picric  Acid   145 

Derivatives  of  Picric  Acid   146 

Rosolic  Acid   147 

Coralline  or  Azuline.   148 

Derivatives  of  Naphthalin. — Naphthylamine  Yellow      ....  149 

Benzoic  and  Chloroxynaphthalic  Acids   150 

Other  applications  of  the  Coal  Tar  colouring  matters     .       .       .  .152 


ANILINE 

AND  ITS  DERIVATIVES. 


 4  

CHAPTER  I. 
BENZOL. 

It  is  advisable  to  commence  with  this  substance,  as  it  may 
be  considered  the  basis  of  the  aniline  industry. 

Benzol,  or  benzine,  may  be  obtained  quite  pure  by  dis- 
tilling benzoic  acid  with  three  times  its  weight  of  hydrate  of 
lime. 

By  the  action  of  heat  upon  the  acid,  benzol  is  formed, 
whilst  carbonic  acid  combines  with  the  lime.  The  process 
is  represented  by  the  following  equation : — 

CI4H503,HO    +    2CaO    =    2CaOC02    +  CI2H6. 

Benzoic  acid.  Lime.         Carbonate  of  lime.  Benzol. 

By  this  process  the  benzol  is  obtained  as  a  colourless, 
very  mobile  fluid,  of  the  specific  gravity  0*85. 

It  boils  at  850  C,  and  its  vapour  density  is  2'38.  Cooled 
to  o°  it  becomes  solid,  forming  crystals  which  liquefy  only 
at  70.  It  is  insoluble  in  water,  but  can  be  mixed  with  alcohol, 
or  ether,  in  any  proportion. 

In  its  chemical  character  benzol  may  be  considered  as  a 
compound  of  the  organic  radical  phenyl  (CI2H5),  with 
hydrogen,  so  that  its  constitution  may  be  expressed  by  the 
formula  (CI2H5)H.  Hence  we  may  call  it  phenylated 
hydrogen. 

B 


2 


BENZOL. 


In  large  quantities  this  substance  is  found  in  the  products 
of  the  distillation  of  coal,  and  coal  tar  is  the  source  whence  we 
extract  benzol  for  technical  purposes.  In  the  distillation  of 
coal,  three  sorts  of  products  are  generally  found  : — At  first 
gas  is  formed,  and  generally  coals  are  distilled  for  the 
purpose  of  manufacturing  illuminating  gas.  This  gas 
consists  of  light  and  heavy  hydrocarbons,  especially  the 
hydrocarbons  C4H4  and  C2H4,  carbonic  acid,  oxide  of 
carbon,  hydrogen,  together  with  accidental  admixture  of 
nitrogen,  &c.  In  the  distillation  of  coal  for  gas  a  liquid  is 
obtained  in  the  receivers,  which  when  investigated  is  found 
to  consist  of  two  different  products,  viz.,  coal  tar  and  am- 
moniacal  water.  The  latter  can  be  easily  separated  from 
the  tar,  and  is  then  used  for  making  salts  of  ammonia  :  this 
need  not  be  considered  further  here.  The  tar  contains  the 
substance  now  under  discussion,  viz.,  the  benzol. 

As  is  generally  known,  tar  is  a  black,  half  liquid,  half 
resinous  mass  of  a  bituminous  odour.  It  is  a  mixture  of  a 
very  great  number  of  organic  compounds,  formed  either 
direftly  or  indirectly  from  the  destructive  distillation  of  coal. 
By  repeated  distillations  the  volatile  contents  of  the  tar  can 
be  easily  separated  from  those  which  do  not  volatilise  by 
heat. 

On  heating  tar  in  a  retort,  benzol  and  other  analogous 
substances,  such  as  toluol,  cumol,  cymol,  &c,  are  at  first 
obtained.  These  compounds  only  differ  from  benzol  in  con- 
taining instead  of  the  radical  phenyl  (CI2H5)  other  radicals, 
such  as  tolyl,  cumyl,  cymyl,  &c.  After  the  benzol  and  its 
homologues  have  passed  over,  on  continuing  the  heat  a  sub- 
stance distils  very  similar  to  the  common  creosote  obtained 
from  wood.  But  the  creosote  obtained  from  coal  tar  has 
the  property  of  crystallising;  it  is  therefore  sometimes 
called  crystallised  creosote.  Its  chemical  names  are  phenic 
acid,  carbolic  acid,  or  hydrate  of  oxide  of  phenyl.  It 
contains  the  same  radical  as  benzol,  viz.,  phenyl;  but 
while  benzol  is  the  compound  of  hydrogen  with  this  radical, 

(CI2H5,  H), 

Phenyl. 


BENZOL. 


3 


phenic  acid  is  the  oxide  of  phenyl  combined  with  one  equivalent 
of  water,  or  CI2H50,  HO. 

When  the  tar  is  freed  from  this  substance  also,  by  con- 
tinuing the  distillation  another  produft  is  obtained  which 
crystallises  in  large  plates,  and  is  apt  to  plug  up  the  con- 
densation tubes ;  hence  much  caution  is  necessary  at  this 
stage.  This  substance  is  naphthalin,  a  hydrocarbon  which 
has  the  formula  C20H8.  This  also  is  of  analogous  compo- 
sition with  benzol,  for  it  is  a  combination  of  the  organic 
radical  naphtyl  (C20H7)  with  hydrogen,  and  should  properly 
be  called  naphthylated  hydrogen. 


When  no  more  naphthalin  distils  over,  by  again  raising 
the  temperature,  a  mixture  is  obtained  of  many  hydrocarbons 
which  have  been  only  imperfectly  investigated,  and  are 
sometimes  sold  under  the  name  of  photogen  oil. 

The  retort  now  contains  a  black  substance,  solid  when 
cold,  and  liquefied  by  heat ;  it  is  called  asphalt. 

The  benzols  obtained  at  first  are  called  light  hydrocarbons, 
to  distinguish  them  from  the  heavy  hydrocarbons,  photogen 
and  solar  oil.  The  production  of  these  two  sorts  of  substances 
is  usually  effected  separately. 

The  light  hydrocarbons,  benzols,  are  produced  by  manu- 
facturers who  wish  to  obtain  asphalt   for   roofing,  &c. 


a.  Thermometer,  b  Opening  closed  by  a  screw,  c.  Boiler  containing  the 
tar.    d.  Cooling  apparatus. 


Fig.  i. 


B  2 


4 


BENZOL. 


By  distillation  they  separate  the  benzols  from  the  other 
contents  of  the  tar,  and  use  the  latter  in  their  manufacture* 
The  distillation  is  effected  over  an  ordinary  fire,  in  common 
boilers  fitted  with  a  cooling  pipe.  A  thermometer  is  placed 
on  the  cupola  of  the  boiler.  At  8o°  C.  the  distillation 
commences.  All  products  obtained  from  8o°  to  ioo°  are 
separately  collected  and  preserved.  When  this  temperature 
is  exceeded  the  receiver  is  changed,  and  the  products  of  dis- 
tillation from  ioo°  to  1300  are  received  in  the  second 
vessel. 

The  benzols  collected  between  8o°  and  ioo°  are  called 
light  benzols,  those  collected  between  ioo°  and  1300,  heavy 
benzols.  These  two  products  are  separately  transformed  into 
nitro-benzols,  and  we  shall  speak  hereafter  of  light  and 
heavy  benzols,  and  of  light  and  heavy  anilines. 

The  benzols  thus  obtained  consist  principally  of  the  hydro- 
carbons benzol  and  toluol,  while  cymol  and  cumol  are 
present  only  in  small  quantities. 

To  give  an  idea  of  the  contents  of  several  species  of  coal 
tar  I  add  here  the  results  of  investigations  made  on  this 
subject  by  Dr.  Grace  Calvert.* 


Benzols. 

Phenic  acid. 

Heavy 
hydrocarb. 

Paraffin. 

|  Naphthalin. 

Dry  tar. 

12 

3 

30 

41 

O 

14  p.c. 

9 

14 

40 

O 

15 

22  „ 

2 

5 

12 

O 

58 

23  „ 

5 

9 

35 

O 

22 

29  >! 

Latterly  manufacturers  have  begun  to  distil  benzol  by 
means  of  steam.  For  this  purpose  steam  is  introduced  into 
the  tar  through  an  iron  tube,  and  the  benzol  is  found  in  the 
receiver  mixed  with  water.  The  benzol  floats  on  the  top, 
and  may  easily  be  separated  pure.  This  method  has  the 
advantage  of  no  fire  being  used,  and  all  danger  of  ignition  is 
thus  done  away  with,  but  the  separation  of  the  light  and 
heavy  benzols  is  very  difficult. 

*  Bulletin  de  la  Soc.  Ind.  de  Mulhouse,  April,  1865.  P.  Schiitzenberger : 
L'histoire  des  Couleurs  d'Aniline.    Comptes  Rendus,  16  August,  1859,  p.  263. 


BENZOL. 


5 


Instead  of  worms,  double  cylinders  are  often  used  to  cool 
the  benzol  vapour,  cold  water  circulating  in  the  intermediate 
space,  while  the  benzol  is  condensed  inside.  But  I  think 
worms  are  better,  on  account  of  their  simplicity  and  cheap- 
ness. For  the  distillation  of  naphthalin,  however,  the 
above-mentioned  cylinders  are  to  be  preferred,  because  they 
cannot  be  easily  obstructed  by  the  naphthalin  crystals. 


CHAPTER  II. 


NITRO-BENZOL. 

When  benzol  is  mixed  with  nitric  acid  it  is  changed  into  a 
yellow  liquid  which  has  a  strong  smell  of  bitter  almonds.  The 
substance  thus  obtained  is  nitro-benzol.  It  was  produced  on 
a  large  scale  before  it  v/as  used  in  the  manufacture  of  aniline 
as  a  substitute  for  bitter  almond  oil,  and  was  employed  in 
perfumeries  under  the  name  of  Essence  of  Mirbane  or  Huile 
dc  Mirbane. 

It  has  already  been  mentioned  that  there  is  a  series  of 
benzol  compounds  boiling  at  different  temperatures  ranging 
from  8o°  to  1300  C.  It  is  therefore  natural  that  there  should 
be  a  corresponding  series  of  nitro-benzols,  boiling  from  2050 
to  2350,  though  the  substance  properly  called  nitro-benzol 
by  chemists,  boils  constantly  at  2130.  It  was  shown  before 
that  the  liquid  obtained  from  coal  tar,  and  commonly 
called  benzol,  consists  of  a  series  of  hydrogen  compounds  of 
phenyl,  tolyl,  cumyl,  cymyl,  &c,  and  that  after  treating  this 
mixture  with  nitric  acid  we  get  the  respective  nitrocom- 
pounds of  the  same  hydrocarbons.  It  must  be  still 
remarked  that  there  is  a  difference  between  the  nitro-benzols 
distilling  at  2050  to  2100,  those  which  distil  at  from  2100  to 
2200,  and  those  which  distil  from  2200  to  2300.  If  the  benzols 
are  separately  treated  with  nitric  acid,  the  benzol  distilling 
at  from  8o°  to  ioo°,  and  that  obtained  at  from  ioo°  to  1300, 
will  differ  considerably  in  their  smell.  The  benzol  first 
obtained  will  yield  a  nitro-benzol  of  a  pure  and  agreeable 


NITRO-BENZOL. 


7 


odour  resembling  that  of  bitter  almonds,  that  distilled 
between  ioo°  and  1300  will  yield  a  nitro-benzol  which  has  a 
disagreeable  odour.  It  is  therefore  only  the  first  product 
that  can  be  used  for  the  purposes  of  perfumery.  The  first 
kind  of  nitro-benzol  is  comparatively  pure,  while  the  other 
kind  contains  nitro-toluol ;  nitro-cumol,  and  nitro-cymol 
being  also  present  in  smaller  quantities. 

To  manufacture  Essence  of  Mirbane  for  perfumery  a  glass 
worm-pipe  is  employed,  divided  at  its  upper  part  in  the  form 
of  a  fork ;  the  whole  being  surrounded  with  cold  water. 
Into  one  of  the  fork-like  branches  is  poured  a  mixture  of 
sulphuric  and  nitric  acids,  the  other  branch  being  fed  with 
benzol.  Both  the  liquids  mix  in  the  worm-pipe,  and  the 
heat  given  off  is  carried  away  by  the  surrounding  water. 

Having  passed  the  pipe,  the  mixture  of  nitro-benzol, 
benzol,  and  the  excess  of  the  acids,  falls  into  a  vessel  filled 
with  cold  water.  The  excess  of  acid  is  there  separated  from 
the  nitro-benzol,  which  is  thus  obtained  pure. 

To  produce  nitro-benzol  on  the  large  scale  necessary  in 
the  manufacture  of  aniline,  the  above-mentioned  apparatus 
cannot  be  used. 

Fig.  2. 


a.  Woulff's  bottle,  b.  Agitator,  c.  Leading  pipe  for  the  vapours,  d.  Vat. 
e.  Woulff's  bottles  containing  water,  f.  Exit  pipe.  g.  Holders  of  the 
vat.    h.  Bottle  with  the  mixtures  of  acids. 


8 


NITROBENZOL. 


At  first  earthen  vessels  were  employed  for  manufacturing 
the  nitro-benzol.  A  WoulfTs  bottle  thoroughly  cooled  with 
water,  is  filled  with  the  benzol,  to  which  a  mixture  of  sul- 
phuric and  nitric  acids  is  added  in  a  small  stream.  As  may 
be  seen  in  the  annexed  drawing  (Fig^),  a  bent  glass  tube  is 
put  into  the  bottle  to  agitate  the  liquid.  From  time  to 
time  a  workman  moves  this  agitator,  and  mixes  the  sub- 
stances contained  in  the  WoulfTs  bottle.  One  neck  of  the 
bottle  is  connected  by  a  tube  to  the  vessel  that  contains  the 
mixture  of  nitric  and  sulphuric  acids.  Instead  of  mixing  the 
two  acids  before  introducing  them  into  the  bottle,  they  may 
be  led  from  two  separate  bottles  into  a  funnel,  where  they 
are  mixed,  and  pass  immediately  into  the  pipe  leading  to  the 
Woulff 's  bottle.  Into  the  middle  neck  is  fixed  the  agitator 
so  that  it  can  be  moved,  and  the  third  neck  bears  a  tube  of 
earthenware,  which  leads  (see  drawing)  through  a  vat  filled 
with  water,  so  that  the  condensed  vapours  may  run  back  into 
the  bottle.  After  passing  the  vat,  the  tube  is  bent  down  to  a 
small  WoulfTs  bottle  filled  with  water,  by  which  the  uncon- 
densed  vapours  (chiefly  N03)  are  led  through  several  WoulfTs 
bottles  before  passing  to  the  chimney. 

The  bottle  is  set  in  a  wooden  vat  through  which  a  current 
of  cold  water  or  of  steam  may  be  led. 

By  treating  benzol  with  nitric  acid,  nitro-benzol  and  water 
are^formed,  thus  : —  t  h  v  0  -1   j  -f^ 

Cx2H5,  H  +  N05  =  CI2H5,  N04  +  HO. 

Benzol.  Nitro-benzol. 

On  the  production  of  nitro-benzol,  water  is  always  formed  ; 
this  when  free  would  dilute  the  nitric  acid  so  much  that 
it  would  be  no  longer  strong  enough  to  transform  the 
benzol,  since  only  strong  nitric  acid  can  effeCt  this  change. 
Hence  we  always  add  to  the  nitric  acid  a  quantity  of 
sulphuric  acid,  which  combines  with  the  water  formed  at 
the  moment  of  change. 

At  the  commencement  of  the  process  cold  water  is  led 
through  the  vat  surrounding  the  bottle  ;  but  when  the  greater 
portion  of  the  nitric  acid  has  been  added,  and  the  first  violent 
action  is  over,  by  passing  steam  into  the  vat  this  water  is 


NITRO-BENZOL. 


9 


gradually  heated,  and  now  the  last  reaction  is  effected  on  the 
benzol  remaining  in  the  bottle. 

As  the  manufacture  of  aniline  increased,  the  Woulff's  bottle 
was  found  too  small  to  produce  nitro-benzol  on  a  suffi- 
ciently large  scale.  These  vessels  of  earthenware  were  also 
so  fragile  that  it  was  dangerous  to  work  with  them.  Hence 
aniline  manufacturers  had  to  choose  other  vessels. 

Iron  is  attacked  by  most  acids,  also  by  nitric  acid  when 
diluted ;  but  if  the  nitric  acid  is  very  concentrated  and 
evolves  yellow  vapours,  iron  is  no  longer  affeCted  by  it ;  neither 
does  a  mixture  of  nitric  and  sulphuric  acids  affeCt  iron. 
Hence,  for  making  nitro-benzol,  manufacturers  now  use 
large  iron  cylinders,  in  which  an  iron  agitator  is  fixed,  as 
shown  in  Fig.  3.    This  agitator  is  moved  by  a  pair  of 

Fig.  3. 


10 


NITRO-BENZOL. 


wheels.  The  benzol  is  introduced  through  an  opening  in  the 
lid  of  the  cylinder,  after  which  the  opening  is  closed.  Through 
another  opening  in  the  lid  a  glass  tube  passes,  which  serves 
to  introduce  the  mixture  of  sulphuric  and  nitric  acids  into 
the  cylinder.  A  third  opening  admits  a  tube  of  earthenware, 
which  conducts  the  vapours,  formed  by  the  adtion  of  nitric 
acid  on  the  benzol,  to  a  long  cooling  pipe.  At  the  bottom  of 
the  cylinder  an  iron  pipe  leads  to  an  earthenware  tap,  through 
which  the  nitro-benzol  can  be  drawn  off.  The  cylinder 
is  surrounded  by  an  iron  vessel  containing  water.  This 
water  is  also  renewed  at  the  commencement,  and  heated 
towards  the  close  of  the  operation.  After  filling  the  cylinder 
for  a  quarter  of  its  height  with  benzol,  and  having  begun  to 
agitate,  the  mixture  of  acids  is  introduced  through  the  above 
pipe.  Gradually  the  contents  of  the  cylinder  become 
heated,  which  heat  is  prevented  from  becoming  too  strong 
by  changing  the  water  in  the  surrounding  vessel.  When  the 
whole  quantity  of  nitric  acid  has  passed  into  the  cylinder 
the  surrounding  water  is  heated,  whereby  the  remaining 
benzol  is  transformed  into  nitro-benzol.  When  the  aftion  is 
over,  the  contents  of  the  cylinder  are  drawn  off  through  the 
tap,  and  washed  with  water.  This  washing  dissolves  out 
the  acids  from  the  nitro-benzol.  The  nitro-benzol  sinks  to 
the  bottom  of  the  vessel  containing  the  water,  and  the  con- 
tents of  the  cylinder  can  be  collected  by  means  of  a  separa- 
ting funnel.    It  is  then  ready  to  be  used  for  making  aniline. 

To  obtain  nitro-benzol  on  a  large  scale,  12  parts  of  benzol 
are  employed,  together  with  a  mixture  of  13  parts  of  fuming 
nitric  acid  and  8  parts  of  sulphuric  acid. 

The  nitro-benzol  obtained  as  before-mentioned  is  pure 
enough  for  the  manufacture  of  aniline ;  but  if  it  is  to  be 
used  as  a  substitute  for  oil  of  bitter  almonds,  it  must  be 
once  more  distilled  by  means  of  steam.  The  nitro-benzol 
is,  in  this  case,  put  into  an  iron  retort  heated  from  below, 
and  superheated  steam  is  passed  through  the  nitro-benzol. 
A  distillate  is  obtained  which  contains  water  and  nitro- 
benzol  ;  the  latter  soon  sinks  to  the  bottom. 

The  reason  why  the  mixture  of  nitric  acid  and  benzol 
must  be  cooled,  is  to  prevent  a  too  sudden  and  strong  reaction 


NITRO-BENZOL. 


II 


of  the  nitric  acid  on  the  benzol.  When  too  strong  this  re- 
action no  longer  yields  pure  nitro-benzol,  but  another  product, 
differing  from  nitro-benzol  by  containing  one  equivalent  more 
of  nitrous  acid.    This  produft  is  binitro-benzol  CI2H4(N04)2. 

This  is  not  adtually  injurious,  but  by  its  transformation 
into  aniline  nitraniline  is  formed,  which  is  quite  useless  in 
the  manufacture  of  aniline  colours.  As  maybe  easily  shown, 
binitro-benzol  has  a  greater  density  than  common  nitro- 
benzol,  and  also  nitraniline  is  heavier  than  common  aniline. 
But  being  useless  in  the  manufacture  of  aniline  colours, 
nitraniline  can  only  be  looked  upon  as  so  much  loss  and  a 
diluent  of  true  nitro-benzol. 


CHAPTER  III. 
ANILINE. 

Aniline  is  found  already  formed  in  coal  tar.  M.  Runge 
enumerated  among  the  alkaline  products  of  coal  tar,  pyrrhol, 
aniline  (called  by  him  cyanol),  and  leukoline.  Picoline,  naph- 
thalin,  and  paranaphthalin  were  also  found  by  MM.  Anderson 
and  Anders.  The  aniline  in  tar  is  the  produft  of  the  adtion 
of  pheilic  acid  on  ammonia.  At  first  these  two  substances 
yield  a  compound  phenate  of  ammonia 
NH40,  C££, 

Ammonia     Phenic  acid. 

which  -at  a  high  pressure  is  transformed  into  aniline  and 
water, 

NH40,  CI2H5Q  =  CI2H7N  +  2HO. 

Phenate  of  ammonia.  Aniline.  Water. 

By  treating  the  heavy  hydrocarbons  with  dilute  hydro- 
chloric acid  aniline  is  dissolved  from  them  in  the  form  of 
hydrochlorate,  which  can  be  obtained  in  the  dry  state  by 
evaporating  the  solution.  From  this  salt  aniline  may  be 
easily  got  by  distillation  with  lime  or  potash.  In  the  tar 
oils  a  small  quantity  of  this  substance  remains,  but  much 
too  small  to  allow  it  to  be  extracted  profitably.  Hence 
aniline  must  be  produced  artificially.  Analogous  to  the  pro- 
bable formation  of  aniline  from  the  phenate  of  ammonia,  this 
salt  may  be  submitted  to  high  pressure  by  heating  in  sealed 


ANILINE, 


13 


iron  vessels,  whereby  it  is  changed  into  aniline  and  water. 
This  method  of  producing  aniline  is  a  discovery  of  MM. 
Hofmann  and  Laurent.  Till  now,  however,  they  have  not 
succeeded  in  employing  it  for  technical  purposes.* 

This  mode  of  producing  aniline  led  the  discoverer  to  con- 
sider it  an  amide  of  the  organic  radical  phenyl, 


and  to  call  it  phenylamide. 

We  may  then  consider  aniline  to  be  an  ammonia  in  which 
one  equivalent  of  hydrogen  is  replaced  by  the  radical  phenyl, 


As  the  ammonia  itself  combines  when  forming  salts  with  one 
equivalent  of  hydrogen  to  form  the  hypothetical  metal 
ammonium  NH4,  so  does  aniline  or  phenylamine  also  unite 
with  one  equivalent  of  water  when  it  combines  with  an  acid 
to  form  a  salt.    For  instance^  the  sulphate  of  aniline 

is  represented  by  the  formula 


Long  before  M.  Runge  discovered  aniline  in  coal  tar,  M. 
Unverdorben,  the  first  discoverer  of  this  base,  produced  it 
in  1826  by  heating  indigo.  M.  Fritzsche  showed  in  1840 
that  by  treating  indigo  with  a  solution  of  caustic  potash, 
by  which  process  indigo  is  transformed  into  anthranilic  acid, 
and,  after  drying,  heating  the  mass  thus  obtained,  aniline 
might  be  got.    Isatate  of  potash  also  yields  aniline  by  heat. 

It  is  almost  unnecessary  to  say  that  none  of  these  methods 
of  producing  aniline  can  be  used  to  manufacture  it  on  the 
large  scale ;  indeed  the  only  method  of  producing  aniline 
for  commercial  purposes  is  that  of  the  reduction  of  nitro- 
benzol. 

*  A.  W.  Hofmann,  41  Reports  by  the  Juries."  London,  1863. 


CI2H7N  =  (CI2H5)H2N, 


Aniline. 


Phenyl  amide. 


H 
H. 


*4 


ANILINE. 


As  mentioned  above,  the  formula  of  nitro-benzol  is 

CI2H5N04, 

and  that  of  aniline 

CI2H7N. 

The  two  substances  differ  from  one  another  only  by  the 
addition  of  i  equivalents  of  hydrogen  and  the  subtraction  of 
4  equivalents  of  oxygen,  the  quantities  of  carbon  and 
nitrogen  being  equal.  It  will,  therefore,  be  easily  under- 
stood that  .  by- 'adding  6  equivalents  of  hydrogen  to  nitro- 
benzoj/'ahiline  may  be  produced — 

CI2H5N04  +  6H  =  CI2H7N  +  4HO. 

Nitro-benzol.  Aniline. 

Already  in  1842*  M.  Zinin  found  that  by  adding  sulphide  of 
ammonium  to  a  solution  of  nitro-benzol  in  alcohol,  an  organic 
base  could  be  produced  which  he  called  benzidam,  and 
which  M.  Fritzsche  proved  later  to  be  identical  with  aniline. 

In  1854  M.  Bechamp  found  that  ferrous  salts  of  weak 
acids,  such  as  the  acetate  of  the  protoxide  of  iron,  could  be 
used  for  reducing  nitro-benzol,  by  transforming  it  into 
aniline.  He  employed  direftly  iron  filings,  and  acetic  acid 
in  which  the  nitro-benzol  was  dissolved. 

The  best  proportions!  were  found  to  be  1  part  of  nitro- 
benzol  to  i#2  parts  of  iron. 

This  method  is  now  the  only  one  used  in  the  manufacture 
of  aniline  on  the  large  scale. 

The  apparatus  employed  for  this  manufacture  consists  of  a 
closed  iron  cylinder  (Fig.  4),  in  which  an  iron  agitator  works. 
An  iron  tube,  g,  conducts  from  the  lid  of  the  cylinder  to  a 
worm,  while  another  iron  tube,  d,  entering  the  apparatus, 
reaches  almost  down  to  the  bottom,  and  serves  to  introduce 
steam  from  a  boiler.  On  the  lid  of  the  cylinder  an  iron 
funnel,  k,  is  placed,  which  can  be  stopped  with  a  wooden 
plug ;  this  serves  to  introduce  iron  filings.  Finally,  through 
the  lid  a  tube,  i,  enters  the  cylinder,  for  introducing  a  mixture 
of  acetic  acid  and  nitro-benzol. 

At  first  a  portion  of  iron  filings  is  introduced  into  the 
apparatus,  together  with  a  little  water.  On  this  a  quantity  of 

*  Erdmann,  Journ.  f.  pr.  Chem.,  vol.  62,  p.  469. 

f  Hofmann  found  in  1856,  that  it  was  better  to  use  2*5  parts  of  iron. 
Erdmann,  Journ.  f.  pr.  Chem.,  vol.  67,  p.  131. 


ANILINE. 


15 


the  strong  acetic  mixture  is  poured,  and  as  the  reaction 
becomes  more  vehement  more  acetic  acid  and  nitro-benzol 
is  added,  together  with,  sometimes,  a  little  water.    When  the 


Fig.  4. 


a.  Iron  cylinder,  b.  Lid  of  the  iron  cylinder,  c.  Wheels,  d.  Tube  intro- 
ducing steam.  e.  Iron  funnel  with  tap.  /.  Cupola,  g.  Cooling  pipe. 
h.  Vat.  i.  Pipe  for  introducing  the  acid.  k.  Iron  funnel  with  wooden 
stopper  for  introducing  the  iron  filings. 


aftion  becomes  quieter  more  iron  filings  are  introduced. 
The  quantities  used  are  as  follows  : — 150  parts  of  wrought 
iron,  100  parts  of  nitro-benzol,  and  50  parts  of  strong  acetic 
acid  made  from  wood.  On  commencing  the  manufacture 
it  will  be  well  to  take  100  parts  of  acetic  acid,  as  the  work- 
ing is  easier  with  this  larger  quantity.  Afterwards  it  may 
be  diminished  to  50.  During  the  whole  operation  agitation 
must  be  continued. 

The  heat  produced  by  the  reaction  of  the  different  sub- 
stances is  not  sufficient  to  change  all  the  nitro-benzol  into 
aniline,  and  the  transformation  must  be  completed  by  the 
introduction  of  steam  at  the  end  of  the  operation.  This  will 
cause  a  certain  part  of  the  contents  of  the  cylinder  to  distil 


i6 


ANILINE. 


over ;  it  may  be  caught  in  a  receiver,  and  re-introduced  into 
the  apparatus,  until  no  more  undecomposed  nitro-benzol  is 
found  in  the  distillate.  When  this  is  found  to  consist  only 
of  aniline,  water,  and  acetic  acid,  the  operation  may  be  con- 
sidered complete,  and  the  contents  of  the  apparatus  are  now 
distilled  until  only  oxide  of  iron  remains  behind. 

In  this  operation  acetic  acid  and  iron  are  transformed,  by 
the  decomposition  of  water,  into  acetate  of  the  protoxide  of 
iron,  which,  under  the  influence  of  heat  and  the  oxygen  in 
the  nitro-benzol,  is  transformed  into  acetate  of  the  peroxide 
of  iron,  and  then  to  hydrated  oxide  of  iron.  The  aniline, 
which  is  a  base,  as  we  have  shown,  similar  to  ammonia, 
combines  with  acetic  acid,  but  by  distillation  the  compound 
is  destroyed,  and  in  the  receiver  a  very  dilute  solution  of 
acetic  acid  and  aniline  oil  is  collected,  which  latter  after 
some  time  separates  from  the  water  and  may  be  taken  off. 
In  a  well  conducted  operation  66  parts  of  aniline  may  be 
obtained  from  100  parts  of  nitro-benzol.  Theory  demands 
75,  but  this  result  is  never  attained  in  practice. 

In  case  too  much  iron  filings  have  been  used,  there  is  not 
so  much  as  66  per  cent  of  aniline  obtained,  and  after  finish- 
ing the  operation  and  opening  the  cylinder  there  will  be 
found  a  tarry  brown  mass  mixed  with  the  oxide  of  iron. 
This  substance  is  produced  by  the  too  rapid  reduction  of 
nitro-benzol,  and  the  removal  of  oxygen  from  the  combi- 
nation without  touching  the  hydrogen.  M.  Mitscherlich, 
who  discovered  this  substance  in  1834,*  called  it  azobenzol — 
because  it  consists  of  a  combination  of  nitrogen  (azote)  and 
the  radical  phenyl — (CI2H5,  N).  It  is  possible  to  transform 
the  azobenzol  into  aniline  by  adding  two  equivalents  of 
hydrogen  ; 

CI2H5N    +    2H    =  CI2H7N. 

Azo-benzol.  Aniline. 

This  is  effected  by  treating  it  with  ammonia  and  sulphu- 
retted hydrogen  gas. 

By  saturating  the  distillate,  after  separating  the  aniline 
from  it,  with  soda,  and  evaporating,  acetate  of  soda  is  pro- 
duced. 

*  Poggend.  Ann.,  vol.  xxxii.,  p.  224, 


ANILINE. 


17 


Previous  to  the  employment  of  the  above  method  of  pro- 
ducing aniline,  nitro-benzol  was  reduced  by  a  mixture  of  hydro- 
chloric acid  and  iron ;  in  this  case  the  process  is  the  same, 
except  that  hydrochloric  acid  is  substituted  for  acetic  acid. 

As  hydrochloric  acid  is  much  cheaper  than  acetic  acid, 
the  process  ought  to  be  more  economical.  But  nitro-benzol 
will  not  mix  with  hydrochloric  acid,  though  it  will  easily 
with  acetic  acid ;  hence,  at  the  same  time,  alcohol  must  be 
added  to  the  mixture,  in  order  to  dissolve  the  nitro-benzol, 
and  enable  it  to  be  transformed  into  aniline.  In  this  case 
the  aniline  is  obtained  in  the  form  of  a  hydrochlorate,  which 
being  a  very  stable  salt,  must  be  decomposed  by  distillation 
with  lime.  After  the  operation  in  the  above-mentioned 
apparatus  is  finished,  the  whole  contents  must  therefore  be 
transferred  to  another  retort,  where  the  alcohol  is  distilled 
off,  hydrochlorate  of  aniline  and  chloride  of  iron  remaining. 
The  dry  mass  of  these  two  substances  must  then  be  mixed 
with  lime,  and  again  distilled  with  steam  to  obtain  the  pure 
aniline. 

The  single  operation  described  above  is  in  this  manner 
extended  to  three,  and  a  considerable  loss  of  time  and  of 
alcohol  always  takes  place.  The  method  is  therefore  now 
abandoned  in  all  aniline  manufactories,  the  only  one  em- 
ployed being  that  with  iron  and  acetic  acid. 

After  this  description  of  the  methods  of  producing  aniline 
oil  on  a  large  scale,  we  will  now  give  other  methods  proposed 
by  different  chemists  to  manufacture  aniline,  which  though 
now  not  used  on  a  large  scale,  may  still  become  useful  in  the 
future. 

In  1863,  M.  Kremer*  found  that  aniline  might  be  obtained 
by  heating  nitro-benzol  with  water  and  zinc  powder  as  ob- 
tained in  zinc  manufactories,  t  oxide  of  zinc  being  formed. 
From  100  parts  of  nitro-benzol  he  obtained  63  to  65  parts  of 
aniline.  Zinc  powder  being  at  the  present  time  cheap,  this 
method  may  possibly  be  economically  employed. 

Finally,  M.  C.  WohlerJ  proposed,  as  early  as  1857,  to 

*  Dingler's  Polyt.  Journ.,  169,  p.  377.     Erdmann,  Journ.  f.  pr.  Chem., 
vol.  90,  p.  254. 

f  Dingler's  Polyt.  Journ.,  vol.  168,  p.  158  ;  Polyt.  Centralbl.,  1862,  p.  830. 
I  Erdmann  Journ.,  f.  pr.  Chem.,  vol.  71,  p.  254. 

C 


i8 


ANILINE. 


transform  nitro-benzol  into  aniline  by  means  of  an  alkaline 
solution  of  arsenious  acid.  M.  Wohler  introduced  a  thin 
current  of  nitro-benzol  into  a  retort  in  which  was  boiling  a 
solution  of  arsenious  acid  in  very  strong  potash  (360  of 
Beaume).  Aniline  distilled  over  mixed  with  water,  whilst 
there  remained  in  the  retort  a  solution  of  arseniate  of 
potash. 

Theoretically  considered,  aniline  belongs  to  the  large 
number  of  organic  compounds  which  are  called  amide  bases, 
because  they  all  have  a  composition  similar  to  ammonia, 
one  equivalent  of  the  hydrogen  being  replaced  in  them 
by  an  organic  radical. 

We  know  many  series  of  organic  radicals  whose  formulae 
correspond,  and  to  one  of  these  series  belong  the  radicals  of 
the  substances  which  form  aniline  oil. 

The  algebraic  type  for  these  radicals  isC2nH2n-.7.  The 
series  of  radicals  belonging  to  this  type  is — 

CI2H5  Phenyl. 

CI4H7  Tolyl. 

CI6H9  Xylyl. 

dsHu  Cumyl. 

C20HI3  Cymyl. 

By  the  combination  of  one  equivalent  of  hydrogen  with 
these  radicals  various  substances  are  formed,  some  of  which 
have  been  already  mentioned  ; 

CI2H5,  H  =  Benzol. 

CI4H7,  H  =  Toluol. 

CI6H9,  H  =  Xylol. 

Cl8HII,  H  =  Cumol. 

C20HI3,  H  =  Cymol. 
When  these  radicals  occur  in  combination  similar  to  that 
of  ammonia  (NH3),  so  that  one  equivalent  of  the  hydrogen 
of  this  substance  may  be  viewed  as  being  replaced  by  one  of 
radical,  the  bases  are  formed  of  which  commercial  aniline 
oil  consists, — 

(CI2H5 

Nj     H  =  Phenylamine  =  Aniline. 


ANILINE. 


19 


N 


N 


N 


CI4H7 
H 
H 


Tolylamine  =  Toluidine. 


H  =  Xylylamine  =  Xylidine. 
H 

CisHu 

H  =  Cumylamine  =  Cumidine. 
H 


IC2ofiI3 
H  = 
H 


Cymylamine  =  Cymidine. 


N 


All  these  substances  are  bases,  and  are  very  similar  to  one 
another. 

When  combined  with  acids,  aniline  and  its  homologues 
unite  with  one  equivalent  of  water,  so  that  we  must  write 
sulphate  of  aniline,  for  instance, 
(CI2H5 

H  0>S03. 
H 

Before  speaking  of  aniline  oil  in  general,  it  will  be  well  to 
describe  particularly  the  various  substances  of  which  it 
consists.    The  first  of  which  we  will  speak  is  aniline. 

Aniline  when  pure  is  a  colourless  mobile  oil,  which  can 
be  cooled  to — 200  C.  without  freezing.  Its  specific  gravity  at 
i6°C.  is  i"020.  It  boils  at  1820  C.  It  volatilises  at  the  ordi- 
nary temperature  of  the  atmosphere,  and  if  dropped  on 
paper  disappears  after  some  time.  It  can  be  mixed  with 
alcohol,  ether,  aldehyd,  and  volatile  and  fixed  oils  in  every 
proportion.  It  is  slightly  soluble  in  water,  from  which  it 
may  be  precipitated  by  common  salt.  When  lighted  it  burns 
with  a  large  smoky  flame,  and  must  therefore  be  regarded 
as  a  dangerous  combustible.  When  exposed  to  the  atmo- 
sphere it  assumes  a  red  colour,  which  disappears  again  on 
distillation.    It  is  somewhat  poisonous. 

Of  the  reactions  of  aniline,  the  most  delicate  is  that  pro- 
duced with  hypochlorites.  Aniline  added  to  a  solution  of 
bleaching  powder  in  water  produces  a  blue-violet  colour, 

c  z 


20 


ANILINE, 


changed  by  acids  to  red.    One  of  the  discoverers  of  aniline, 
.  M.  Runge,  was  well  acquainted  with  this  reaction. 

Dilute  sulphuric  acid  yields  with  aniline  or  with  a  solution 
y  :  of" -.aft-  'aniline  salt,  a  white  or  reddish  precipitate  of  sulphate 
— T>f  aniline.  If  aniline  is  employed,  the  whole  solution  changes 
into  a  white  magma. 

Hydrochloric  acid  yields  with  pure  aniline  a  magma  of 
crystals. 

A  glass  rod  moistened  with  hydrochloric  acid  produces 
when  held  over  aniline  a  white  cloud  of  hydrochlorate  of 
aniline. 

Nitric  acid  mixed  with  aniline  yields  after  some  time  blue 
and  green  efflorescences. 

Aniline  is  expelled  from  its  salts  by  alkalis,  and  also  by 
ammonia  at  the  ordinary  temperature,  but  when  heated 
aniline  expels  ammonia  from  its  salts. 

When  aniline  or  a  salt  of  this  base  is  mixed  with  some 
drops  of  sulphuric  acid,  and  a  little  bichromate  of  potash  is 
added,  an  evanescent  blue  colour  is  produced. 

Albumen  is  coagulated  by  aniline.  Pine  wood  and  alder 
pith  when  moistened  with  solutions  of  aniline  salts  assume 
a  dark  yellow  colour,  which  is  not  attacked  by  chlorine. 
According  to  M.  Runge,  this  colour  is  apparent  when  only 
i-5oo,oooth  of  aniline  is  present. 

To  obtain  perfectly  pure  aniline,  common  aniline  is  dis- 
tilled several  times  to  remove  the  tarry  substances,  and  the 
colourless  oil  thus  obtained  is  mixed  with  a  solution  of  oxalic 
acid  in  alcohol.  After  some  hours  oxalate  of  aniline  crystal- 
lises from  the  liquid,  and  this  when  dissolved  and  re-crystal- 
lised several  times,  yields  by  distillation  with  potash  pure 
aniline. 

Sulphate  of  aniline,  CI2H7N,  HO,  S03,  when  dry,  is  a 
white  crystalline  powder,  which  takes  a  reddish  hue  when 
exposed  to  the  atmosphere.  Upon  heating  it,  water  mixed 
with  aniline  volatilises,  an  acid  sulphate  of  aniline  remaining. 
On  continuing  the  heat,  it  yields  a  mixture  of  sulphite  of 
aniline,  ammonia,  and  odorine. 

Sulphate  of  aniline  is  difficultly  soluble  in  cold  water,  easily 
in  hot.    It  is  almost  absolutely  insoluble  in  ether,  and  is 


ANILINE.  21 

with  difficulty  soluble  in  pure  alcohol,  but  motffe  ^Jtsily  inV 
dilute  spirit.  \  ^S>, 

When  mixed  with  nitric  acid,  aniline  yields  f^rate  /Qf\/ 
aniline,  CI2H7N,  HO  N05,  as  a  crystalline  mass. 

Nitraniline  is  a  substance  produced  by  the  substitute 
one  equivalent  of  hydrogen  in  aniline  by  nitric  peroxide 
(N04),  and  is  therefore  expressed  by  the  formula 

It  occurs  in  long  needles  of  a  beautiful  yellow  colour,  which 
being  heavier  than  water  sink  to  the  bottom.  They  liquefy 
at  iio°C.  to  a  yellow  oil,  which  boils  at  285°C.  Nitraniline 
has  a  burning  sweet  taste.  Its  reaction  is  neutral,  although 
it  can  combine  with  acids  to  form  real  salts.  It  dyes 
pine  wood  yellow,  but  is  not  itself  coloured  by  bleaching 
powder. 

It  is  produced  by  treating  dinitro-benzol  with  reducing 
agents,  as  above  described.  (See  page  n.)  It  was  discovered 
in  1846  by  Hofmann  and  Muspratt. 

Hydrochlorate  of  aniline  may  be  easily  produced  by  adding 
hydrochloric  acid  to  aniline.  Its  formula  is  CI2H7N,  HC1. 
It  is  easily  soluble  in  alcohol  or  water.    Its  reaction  is  acid. 

A  solution  of  iodine  in  aniline  soon  forms  crystals  of  hydri- 
odate  of  aniline,  CI2H7N,HI,  and  the  solution  contains  also 
the  hydriodate  of  ioduretted  aniline, 

CI2{f6}N,  HI. 

No  compound  of  aniline  with  carbonic  acid  is  known. 

The  combination  of  aniline  with  acetic  acid  cannot  be 
crystallised  ;  it  volatilises  with  the  vapour  of  water,  in  which 
operation  it  is  decomposed. 

Toluidine  is  contained  in  all  the  aniline  oils  of  commerce. 
It  was  discovered  in  1845  by  MM.  Hofmann  and  Muspratt,* 
and  is  obtained  by  reducing  nitro-toluol.  Common  nitro- 
benzol  being  a  mixture  of  nitro-benzol  and  nitro-toluol,  aniline 
and  toluidine  together  are  obtained  from  it  by  reduction. 


*  Annal.  d.  Chem.  u.  Pharm.,  vol.  liv.,  p.  r. 


22 


TOLUIDINE. 


According  to  the  investigations  of  M.  Chautard,*  it  can  be 
got  by  distilling  the  resin  produced  on  treating  oil  of  turpentine 
with  nitric  acid,  with  a  solution  of  potash. 

I  have  found  that  toluidine  can  be  got  diredtly  from  crude 
aniline  oil  by  transforming  it  by  means  of  oxalic  acid  into 
oxalates,  and  treating  the  mixture  of  these  salts  with  ether. 
This  dissolves  all  other  oxalates  except  oxalate  of  toluidine. 

By  crystallising  this  salt  it  may  be  purified,  and  when  dis- 
tilled with  potash  it  yields  pure  toluidine.  Toluidine  occurs 
in  large  colourless  crystalline  plates,  which  liquefy  at  400  C. 
and  boil  at  198°.  Like  aniline,  it  volatilises  at  the  common 
temperature  of  the  air.    It  has  a  burning  taste. 

With  hydrochloric  acid  vapour  toluidine  yields  clouds  of 
hydrochlorate  of  toluidine  similar  to  those  of  aniline.  By  a 
solution  of  bleaching  powder  it  is  dyed  red,  differing  in  this 
respect  from  aniline. 

Toluidine,  also,  in  acid  solution,  dyes  pine  wood  and  alder 
pith  yellow,  just  as  aniline  does.  By  decomposing  the  salts 
of  toluidine  with  an  alkali,  this  base  is  obtained  in  the  form 
of  a  coagulum  which  rises  to  the  top  of  the  liquid.  It  is 
soluble  in  wood  spirit,  alcohol,  ether,  aceton,  and  also  in 
volatile  and  fat  oils.  The  formula  of  toluidine  is,  as  before 
mentioned,  CI4H9N. 

Sulphate  of  toluidine  can  be  obtained  by  adding  some 
drops  of  sulphuric  acid  to  a  solution  of  the  base  in  ether. 
The  white  crystalline  precipitate  thus  obtained  is  washed 
with  ether  and  crystallised  from  water.  It  is  easily  soluble 
in  water.  This  constitutes  a  difference  between  it  and  the 
sulphate  of  aniline. 

The  hydrochlorate  of  toluidine  is  obtained  as  the-  corre- 
sponding aniline  salt ;  it  can  be  got  in  white  crystalline 
plates,  which  soon  acquire  a  yellow  tinge  in  the  atmosphere. 
It  is  easily  soluble  in  water  and  alcohol,  but  with  difficulty 
in  ether.    Its  solution  has  an  acid  reaction. 

A  solution  of  toluidine  in  alcohol,  when  mixed  with  a 

*  N.  J.  Pharm.,  24,  166.    Journ.  f.  Pra&.  Chem.,  60,  240. 


CHINOLINE. 


23 


similar  solution  of  oxalic  acid,  yields  brilliant  white  needles 
of  binoxalate  of  toluidine, 

CI4H9N,  HO,  C203  +  HO,  C203- 

Toluidine.       Oxalic  Oxalic 
acid.  acid. 

This  salt  is  difficultly  soluble  in  cold  water  and  alcohol ; 
more  easily  when  the  liquids  are  boiling. 

Chinoline  exists  in  general  only  in  aniline  oils  got  direft 
from  heavy  oil  of  tar.  It  was  discovered  in  coal  tar  by  M. 
Runge*  in  1834.  He  called  it  leukol,  while  M.  Gerhardt,t 
who  obtained  the  same  body  by  distillation  of  quinine  and 
quinidine  with  hydrated  potash,  called  it  chinoline.  To  get 
pure  chinoline,  heavy  tar  oils  are  treated  with  hydrochloric 
acid ;  the  solutions  of  hydrochlorates  are  then  evaporated, 
and  the  dry  salts  distilled  with  milk  of  lime.  The  distillate 
which  first  passes  over  is  collected  separately  until  it  no 
longer  turns  bleaching  powder  blue.  As  soon  as  the  colour 
of  the  bleaching  powder  ceases  to  be  affefted  by  the  distillate, 
the  receiver  is  changed  and  the  oil  now  distilling  is  collected  ; 
this  consists  almost  entirely  of  chinoline.  After  dissolving 
it  in  alcohol  an  alcoholic  solution  of  oxalic  acid  is  added, 
which  causes,  after  some  hours,  a  precipitate  of  oxalate  of 
aniline,  the  oxalate  of  chinoline  remaining  in  solution.  After 
separating  the  crystals  from  the  liquid  the  latter  is  distilled 
with  lime,  whereby  first  alcohol  and  then  chinoline  is  ob- 
tained ;  the  latter  is  freed  from  water  by  a  second  distillation 
over  chloride  of  calcium.  The  pure  chinoline  thus  obtained 
is  a  colourless  oil  of  the  specific  gravity  of  1*081  at  io°  C. 
It  boils  at  2390.  Its  odour  is  penetrating,  and  similar  to  that 
of  bitter  almonds  ;  it  is  slightly  poisonous. 

Chinoline  is  not  coloured  by  bleaching  powder,  neither 
does  it  dye  pine  wood.  It  yields,  when  treated  with  a  mix- 
ture of  chlorate  of  potash  and  hydrochloric  acid,  an  orange 
coloured  oil  which  becomes  resinous  when  cold.  This  sub- 
stance is  dissolved  by  hot  alcohol,  and  precipitated  again  when 
the  alcohol  cools.    Aniline  expels  chinoline  from  its  salts. 

*  Poggend.  Ann.,  31,  68. 
f  Journ.  f.  pr.  Chem.,  28,  76. 


24 


ODORINE. 


Chinoline  is  soluble  in  every  proportion  in  bisulphide  of 
carbon,  alcohol,  ether,  aceton,  aldehyd,  but  is  with  difficulty 
soluble  in  water.  It  is  dissolved  both  by  volatile  and  fixed 
oils. 

The  formula  of  this  substance  is  Cl8H7N,  and  the  radical 
contained  in  it  has  therefore  the  composition  Cl8H5. 

Sulphate  of  chinoline,  consisting  of  sulphuric  acid,  the 
base,  and  one  equivalent  of  water,  can  be  easily  got  by  dis- 
solving chinoline  in  ether  and  adding  sulphuric  acid.  A 
thick  liquid  immediately  sinks  down,  which  after  some  days 
solidifies  to  a  mass  of  microscopic  crystals. 

By  treating  chinoline  with  hydrochloric  and  oxalic  acids, 
difficultly  crystallising  salts  are  obtained  which  correspond 
in  composition  with'the  similar  salts  of  toluidine. 

Odorine  is  a  base  of  the  same  composition  as  aniline.  It 
was  discovered  in  1826  by  M.  Unverdorben,*  who  found  it 
in  the  oil  distilled  from  bones  (oleum  animale  foetidum). 
On  account  of  its  very  disagreeable  penetrating  smell  he 
called  this  oil  odorine.  In  1846,  Mr.  Anderson  once  more 
investigated  this  oil  and  called  it  picoline. 

This  substance  is  contained  only  in  very  small  quantities 
in  the  tar  oils,  and  in  still  smaller  quantity  in  aniline  oil, 
but  there  is  quite  sufficient  present  to  give  a  very  disagree- 
able odour  to  the  common  aniline  oil.  To  obtain  this  sub- 
stance pure  is  very  difficult,  and,  according  to  Mr.  Anderson, 
it  is  effected  as  follows  : — The  oil  obtained  on  the  rectification 
of  tar  oil  is  mixed  with  sulphuric  acid,  which  saturates  the 
bases,  forming  the  corresponding  sulphates.  This  solution 
of  the  bases  in  sulphuric  acid  is  separated  from  the  tar  oil 
and  mixed  with  common  ammoniacal  liquid  obtained  in  the 
distillation  of  coal.  Upon  distilling  this  mixture  water  is  at 
first  obtained,  and  then  a  thick  dark  brown  oil  heavier  than 
water,  consisting  substantially  of  odorine,  aniline,  pyrrhol, 
and  benzol,  and  also  of  a  heavy  thick  oil  of  a  neutral  reac- 
tion. Three-fourths  of  this  oil  are  distilled  over,  and  the  last 
fourth  is  left  in  the  retort.  It  consists  of  the  above-men- 
tioned neutral  oil. 


*  Poggend.  Ann.,  8,  259  and  480 ;  11,  59. 


ANILINE. 


25 


The  distillate  is  a  mixture  of  water,  odorine,  and  a  little 
aniline;  it  is  supersaturated  with  sulphuric  acid,  and  distilled. 
In  this  way  a  solution  of  pyrrhol  in  water  is  obtained,  and 
the  sulphate  remaining  in  the  retort  is  then  supersaturated 
with  hydrate  of  potash  and  heated,  whereupon  a  solution  of 
odorine  in  water  distils  over.  To  this,  hydrate  of  potash  is 
added,  which  effedts  the  precipitation  of  the  pure  odorine. 

Odorine  boils  at  1330  C,  and  its  specific  gravity  at  io°  is 
0*955.  Its  smell  is  excessively  disagreeable.  It  does  not 
dye  alder  pith,  pine  wood,  or  become  coloured  by  bleaching 
powder.  Hydrochloric  acid  when  held  over  odorine  gives  rise 
to  clouds  of  white  hydrochlorate  of  odorine.  It  mixes  in  every 
proportion  with  alcohol,  ether,  fixed  and  volatile  oils,  and 
even  with  water,  by  which  latter  circumstance  it  differs  from 
every  other  similarly  composed  substance. 

The  composition  of  odorine  is  similar  to  that  of  aniline, 
viz.,  CI2H7N. 

From  an  oil  which  MM.  Collin  and  Coblentz  had  obtained 
by  distilling  aniline,  and  which  boiled  only  at  a  very  high 
temperature,  Dr.  Hofmann  produced  a  new  base.  He  treated 
a  portion  of  this  oil  which  distilled  at  a  temperature  above 
333°  with  sulphuric  acid,  and  washed  the  resulting  sulphates 
with  water,  whereby  he  separated  an  easily  soluble  from  a 
difficultly  soluble  sulphate.  The  latter  yielded  when  decom- 
posed by  soda  a  thick  basic  oil  which  solidified  after  some 
days.  After  pressing  it  in  bibulous  paper  this  substance  was 
crystallised,  when  it  deposited  in  bright,  silk-like  needles 
which  liquefied  at  a  temperature  of  192°,  and  boiled  at  3600. 
Analysis  gave  the  formula  CI2H7N. 

This  substance  has  therefore  the  same  formula  as  aniline, 
but  differs  from  it  in  properties  ;  hence  it  may  be  called 
"  paraniline." 

Paraniline  forms  well  defined  crystals,  and  Dr.  Hofmann 
thinks  that  paraniline  may  be  obtained  from  aniline  by  sub- 
mitting this  latter  to  a  very  elevated  temperature. 

Common  Aniline  Oil  is  never  pure  aniline  but  always  a 
mixture  of  aniline,  toluidine,  odorine,  &c.  It  is  commonly 
free  from  chinoline,  which  is  contained  only  in  the  oil  imme- 
diately obtained  from  coal  tar. 


26 


ANILINE. 


Aniline  oil  is  a  yellow  or  brown  fluid  of  a  peculiar  disagree- 
able smell,  sometimes,  especially  when  obtained  direftly  from 
coal  tar,  of  a  common  photogen  smell.  It  takes  fire  easily, 
and  must  be  very  cautiously  preserved.  It  is  usually  sold 
in  iron  bottles  surrounded  with  basket-work.  Each  iron 
flask  usually  contains  one  cwt.  of  oil. 

Aniline  oil  begins  to  boil  at  1750  or  i8o°C,  and  almost 
entirely  distils  between  1800  and  2050.  Common  aniline  oil 
never  has  a  constant  boiling  point,  but  in  every  case  a 
thermometer  put  into  the  boiling  fluid  rises  degree  after  degree 
as  ebullition  progresses.  By  comparison  of  the  boiling  points 
of  the  substances  contained  in  aniline  oil  (odorine  1330, 
aniline  1820,  toluidine  1980,  chinoline  2390),  we  find  that 
aniline  oils  boiling  at  a  low  temperature  must  contain  an 
excess  of  undecomposed  benzol  and  odorine.  The  higher 
boiling  points  are  those  of  mixtures  containing  a  larger  pro- 
portion of  toluidine  mixed  perhaps  with  the  more  difficultly 
boiling  homologues  of  aniline,  viz.,  chinoline  and  some  of 
the  heavy  tar  oils.  Undecomposed  nitro-benzol  also  elevates 
the  boiling  point  of  aniline  oil.  When  it  begins  to  boil, 
aniline  oil  yields  a  little  water  and  benzol.  If  these  do  not 
average  more  than  from  2  to  4  per  cent,  no  adulteration  need 
be  suspected. 

It  is  of  the  greatest  importance  for  every  colour  manu- 
facturer to  know  as  readily  as  possible  the  quality  of  an 
aniline  oil  which  he  proposes  to  use  in  making  colours.  But 
up  to  the  year  1867  there  was  no  method  of  investigating 
the  colorific  power  of  aniline  oil,  especially  with  reference 
to  magenta. 

In  this  year  I  made  considerable  investigations  on  this 
subject,  and  was  so  fortunate  as  to  find  a  method  which,  in 
from  a  quarter  to  half  an  hour,  will  detect  whether  an  aniline 
oil  is  capable  of  producing  a  large  or  small  quantity  of 
magenta,  and  which  also  points  out  how  the  defective  oil 
may  be  ameliorated. 

This  method  enables  one  to  render  available  an  aniline 
oil  which  otherwise  could  not  be  used  for  producing  colours, 
by  a  simple  mixture  with  another  oil. 


ANILINE. 


27 


The  method  which  I  discovered  is  so  simple  that  it  is 
strange  that  aniline  manufacturers  have  not  found  it  out 
long  before.  I  shall  describe  it  here  but  briefly,  referring  the 
reader  to  a  more  detailed  account  in  Dingier' s  Polytechnische 
Journal,  July  1867,  vol.  185,  p.  49. 

Almost  every  aniline  oil  is  produced  by  transforming  benzol 
into  nitro-benzol,  and  this  latter  into  aniline.  The  benzols 
are  all  obtained  from  coal  tar,  and  will  therefore  all  contain 
substantially  the  same  hydrocarbons,  though  in  different 
proportions.  We  have  seen  before  that  every  commercial 
benzol  can  be  separated  into  a  portion  that  boils  between 
8o°  and  ioo°,  and  another  that  boils  between  ioo°  and  1300  C.  ; 
and  that  by  dividing  the  benzol  in  this  manner  two  liquids 
are  obtained  which  yield  by  nitrification  two  sorts  of  nitro- 
benzol  of  very  different  smell  and  boiling  points  ;  these,  again, 
yield  two  different  anilines,  commonly  called  light  and  heavy 
anilines.  (I  call  these  two  sorts  Kuphaniline  and  Bar  aniline, 
from  fcovcjx)?  light,  and  fiapv?  heavy.)  It  is  very  easy  to  see  that 
kuphaniline  consists  substantially  of  aniline,  baraniline  con- 
taining but  a  small  quantity  of  this  base,  and  therefore  more 
toluidine.  Both  contain  a  small  quantity  of  water,  unde- 
composed  benzol,  and  nitro-benzol.  Of  course  these  two 
sorts  of  aniline  oil  will  begin  to  boil  at  very  different  tem- 
peratures, and  a  very  different  percentage  of  the  two  oils 
will  distil  when  both  are  heated  to  the  same  temperature. 

To  render  this  difference  clear,  we  may  heat  slowly  a 
certain  quantity  of  any  sort  of  aniline  oil — kuphaniline  or 
baraniline — and  notice  well  the  quantities  of  the  oils  distilled 
at  various  temperatures,  degree  by  degree.  To  simplify  the 
operation,  notice  the  quantities  distilled  during  a  rise  of 
temperature  amounting  to  50.  As  for  practical  purposes  the 
difference  between  the  specific  weights  of  the  two  sorts  of 
oil  is  of  no  importance,  the  quantities  of  distilled  oil  may  be 
determined  by  receiving  them  in  a  graduated  cylinder. 

I  put  100  cubic  centimetres  of  kuphaniline  in  a  glass 
retort,  which  I  placed  in  a  bath  of  oil  or  paraffin  heated  by 
a  lamp.  The  tube  of  the  retort  was  joined  to  a  Liebig's 
condenser,  and  at  the  extremity  of  the  condensing  tube  I 


placed  as  receiver  a  graduated  cylinder  (a)  by  which  the 
number  of  cubic  centimetres  of  distillate  could  be  observed. 
Of  course  the  condensing  apparatus  was  supplied  with  cold 
water.  Having  placed  a  thermometer  in  the  neck  of  the 
retort,  I  began  to  heat. 

At  first  some  drops  of  liquid,  consisting  of  benzol,  a  little 
aniline,  and  water  distilled,  so  that  when  the  mercury  in  the 
thermometer  had  risen  to  1800  C,  cubic  centimetres  had 
distilled,  of  which  2^  were  water,  and  the  rest  a  mixture  of 
benzol  with  a  little  aniline  and  odorine.  By  continuing  the 
heating  the  oil  distilled  in  large  quantities,  so  that  when  the 
thermometer  had  risen  to  1850,  54  cubic  centimetres  had 
distilled  between  1800  and  1850.  Up  to  1900,  34  cubic  centi- 
metres distilled,  so  that  the  remaining  oil  was  only  cubic 
centimetres.  Of  course  another  sample  of  kuphaniline  oil 
will  not  yield  precisely  the  same  numbers,  but  they  will  be 
at  all  events  similar  to  those  above  mentioned. 

When  baraniline  is  heated  in  the  same  manner  up  to  1900, 
from  100  cubic  centimetres  of  the  oil  3  j-  will  be  distilled,  of 
which  2  are  water  and  the  rest  aniline  oil,  with  a  little  unde- 
composed  benzol.  Between  1900  and  195°,  8  cubic  centi- 
metres distil ;  then  up  to  2000,  18 ;  from  2000  to  2050,  39 ; 


ANILINE.   9X) 

from  205  to  210  ,  19  ;  from  2100  to  2150,  7  cubit  centimetres^/ 
5  J  remaining  in  the  retort.  \    W  S 1 '  r  r 

Now,  if  we  compare  the  quantities  of  both  oiis^ktilled  at 
different  temperatures,  we  shall  find  a  great  differencB-pstT 
that  by  distilling  in  the  above  manner  it  is  absolutely  im- 
possible to  mistake  a  kuphaniline  for  a  baraniline,  and  vice 
versa. 

Having  thus  investigated  the  different  sorts  of  aniline  oil 
by  distillation,  we  must  observe  that  every  aniline  oil  can  be 
considered  as  a  mixture  of  kuphaniline  and  baraniline.  Every 
aniline  oil  is  produced  from  benzol,  of  which  one  portion  can 
be  distilled  at  a  temperature  of  from  8o°  to  ioo°,  and  another 
quantity  between  ioo°  and  1300 ;  therefore  every  aniline  oil 
is  a  mixture  of  kuph-  and  bar-aniline.  It  is  easy  to  under- 
stand that  we  may  produce,  by  mixing  direftly  kuph-  and 
bar-aniline,  aniline  oils  of  different  boiling  points.  I  have 
produced  a  series  of  these  mixtures,  and  have  found  that 
every  one  differs  from  every  other  in  the  quantities  of  oil 
which  will  distil  at  different  temperatures. 

I  have  thus  investigated  several  series  of  mixtures  of  kuph- 
aniline and  baraniline  obtained  by  different  operations,  and 
have  carefully  noted  the  results.  The  mean  results  thus 
obtained  I  have  drawn  up  in  the  form  of  a  table. 

Now  it  is  quite  clear  that  any  aniline  oil  similar  in  its 
mode  of  distillation  to  any  one  of  my  artificial  mixtures  will 
be  similar  to  it  also  in  contents,  and  will  be  composed  espe- 
cially of  the  same  quantities  of  kuph-  and  bar-aniline. 

Of  course  this  process  will  not  enable  us  to  recognise  if 
an  aniline  oil  contains  one  per  cent  of  kuphaniline  or  barani- 
line, but  such  minutiae  are  of  no  consequence  in  practice.  I 
have  mixed  the  two  kinds  of  aniline  in  such  a  manner  that 
the  proportions  differ  considerably,  and  have  thus  produced 
a  table  which  enables  any  one  to  recognise  the  nature  of 
every  aniline  oil  found  in  commerce,  and  to  produce  by  simple 
mixture  from  two  sorts  of  aniline,  useless  for  manufacture, 
another  sort  which  yields  very  good  results. 


30 


ANILINE. 


I  have  mixed — 
90  per  cent  kuphaniline  with  10  per  cent  baraniline. 
85  „  15 


80 
75 

60 
50 
37i 
25 


20 
25 
37k 
40 

5o 

62^ 

75 


By  adding  to  the  results  thus  obtained  the  numbers  men- 
tioned above,  found  by  distilling  pure  kuphaniline  and  bar- 
aniline,  I  have  constructed  the  following  table  : — 


Deg.  C. 

100  K 
oB 

go  K 
10  B 

85  K 
15  B 

80  K 
20  B 

75  K 
25  B 

62I  K 
37*  B 

60  K 
40  B 

50  K 
50  B 

37*  K 
62k  B 

25  K 
75  B 

100  K 
100  B 

1800 

2* 

7 

2* 

5* 

31 

4 

4 

2 

3 

6 

3i 

3 

3 

2 

2* 

1850 

54 

50 

29* 

22 

51 

2* 

7 

4* 

2* 

2 

1900 

34 

34 

55* 

41 

37 

7* 

5* 

4* 

1* 

195° 

5 

8£ 

15 

25 

33 

42 

40 

17 

8 

200° 

9 

8* 

19 

28! 

36 

18 

205° 

4* 

5 

16 

10 

11 

16 

39 

2IO° 

4* 

3* 

7* 

8 

19 

215° 

4* 

7 

Residue 

3* 

4 

4 

8* 

3i 

6* 

7 

6* 

3* 

5 

5* 

In  this  way  I  distil  every  aniline  oil  whose  nature  I  wish 
to  study,  and  seek  in  the  above  table  the  series  of  results 
most  similar  to  those  obtained  by  the  distillation.  Thus  the 
nature  of  any  aniline  oil  can  be  ascertained  as  accurately  as 
is  necessary  in  practice  in  from  a  quarter  to  half  an  hour. 

For  manufacturing  magenta  an  aniline  oil  of  a  certain 
composition  must  be  used.  Some  aniline  oils  yield  very  good 
results,  others  very  bad  ones,  and  it  was  not  possible  for- 
merly to  discover  whether  a  particular  aniline  oil  could  be 
used  advantageously  for  this  manufacture  or  not.  I  have 
investigated  a  great  number  of  aniline  oils  which  have  yielded 
good  results  in  various  manufactories.  On  distillation  I 
found  them  to  be  of  similar  composition  to  a  mixture  of  75 
kuphaniline  and  25  baraniline  ;  hence  we  are  led  to  conclude 
that  this  mixture  is  the  most  favourable  to  the  manufacture 


ANILINE. 


31 


of  magenta.  But  I  shall  speak  of  this  subject  again  in 
another  place. 

I  must  here  remark  that  by  investigating  kuphaniline  and 
baraniline  I  have  found  the  composition  of  the  former  to  be 
90  per  cent  aniline,  5  per  cent  toluidine,  and  5  per  cent 
odorine  and  water.  Baraniline  consists  of  70  per  cent  tolui- 
dine and  30  per  cent  of  the  homologues  of  aniline  and  tolui- 
dine, which  boil  at  a  more  elevated  temperature. 

This  method  of  analysis,  together  with  the  details  of  my 
investigations  respecting  the  determination  of  aniline  oil, 
will  be  found  in  the  above-mentioned  page  of  Dingler's  Pol. 
Journal. 

We  thus  become  acquainted  with  the  true  nature  and  com- 
position of  aniline  oil,  and  are  enabled  to  recognise  in  a  short 
time  the  properties  of  any  sample  of  this  substance. 

It  will  be  useful  here  to  add  some  remarks  on  the  poisonous 
nature  of  aniline.  Professor  Letheby  published  some  very 
remarkable  notes  on  this  subject  which  I  cannot  forbear 
mentioning.  According  to  Letheby,  aniline  has  a  narcotic 
effeCt  on  the  animal  organism.  Taken  in  doses  of  from  1  to 
7  grammes  it  has  a  dyeing  aCtion  on  the  organism.  The 
features  of  the  person  who  has  taken  the  poison  become 
bluish,  the  lips  and  jaw  turn  bluish  grey,  &c.  The  salts  of 
aniline  are  much  less  poisonous  than  aniline  itself.  It  has 
long  been  known  that  nitrobenzol  is  poisonous  only  because 
it  becomes  reduced  to  aniline  in  the  stomach. 

Aniline  poisoning  can  easily  be  recognised  as  follows  : — - 
The  contents  of  the  stomach  of  the  poisoned  person  are 
macerated  with  water  containing  a  little  sulphuric  acid.  The 
mass  thus  obtained  is  distilled,  after  mixing  with  an  excess 
of  potash  solution.  The  distillate  is  carefully  collected,  and 
after  the  addition  of  a  little  sulphuric  acid,  is  evaporated.  If 
aniline  be  present,  at  the  top  of  the  solution  where  its  level 
touches  the  vessel,  a  purple  or  red  margin  is  found;  i-2000th 
grain  of  aniline  can  be  well  recognised  in  this  manner  by 
evaporating  in  a  platinum  vessel  which  is  connected  with 
the  positive  pole  of  a  galvanic  battery,  the  negative  eleftrode 


32 


ANILINE. 


being  in  the  fluid.  The  nascent  oxygen  at  the  positive  pole 
oxidises  the  aniline  present,  and  produces  coloured  com- 
pounds. It  has  often  been  observed  by  aniline  manufacturers 
that  the  workmen  not  only  suffer  from  the  use  of  arsenic, 
but  also  from  that  of  aniline,  especially  when  they  work  in 
apartments  where  aniline  vapours  are  mixed  with  steam. 


CHAPTER  IV. 


MAGENTA, 

Although  not  discovered  first,  it  is  preferable  to  begin  with 
the  red  colouring  matter  derived  from  aniline. 

In  this  chapter  I  shall  describe  the  several  methods  of  pre- 
paring a  red  dye  from  aniline,  and  I  shall  call  these  aniline 
reds  magenta,  because  till  now  it  was  not  proved  that  there 
was  any  other  red  aniline  colour  besides  magenta. 

As  regards  the  aniline  used  in  the  manufacture  of  magenta, 
Hofmann*  has  proved  that  neither  pure  aniline  nor  pure 
toluidine  are  able. to  produce  this  colour,  but  only  a  mixture 
of  both  the  above-mentioned  bases.  I  shall  speak  on  this 
subject  again  when  I  discuss  the  theory  of  the  formation  of 
aniline  red. 

I  have  already  shownt  that  an  aniline  oil  consisting  of  75 
per  cent  kuphaniline  and  25  per  cent  baraniline  may  be  best 
employed  in  the  manufacture  of  aniline  red.  By  this  analysis 
of  the  two  sorts  of  aniline  oil  we  are  able  to  determine  the 
quantities  of  pure  aniline  and  toluidine  which  will  yield  the 
largest  quantity  and  the  best  quality  of  magenta,  viz.,  a 
mixture  of  three  parts  of  aniline  with  one  part  of  toluidine, 
the  other  contents  of  aniline  oil  being  indifferent  as  regards 
the  manufacture  of  magenta. 

*  Comptes  Rendus,  part  56,  p.  1062. 
f  Dingler's  Pol.  Journ.,  1867,  pp.  185,  189. 
D 


34 


MAGENTA. 


Of  the  transformation  of  this  mixture  into  magenta  we 
shall  speak  hereafter. 

Magenta  was  first  known  under  the  name  of  fuchsine,  which 
name  is  still  general  in  France  and  Germany.  The  name 
is  taken  from  the  name  of  a  flower  having  a  colour  very 
similar  to  magenta,  the  fuchsia  codinea.  From  it 
fuchsiacine  was  at  first  formed,  which  was  then  soon  abbre- 
viated to  fuchsine.  The  colour  was  introduced  into  com- 
merce about  the  time  of  the  battles  of  Magenta  and  Solferino  ; 
hence  the  name  now  most  generally  used  to  denote  this 
bright  bluish  red  colouring  matter. 

The  red  colouring  matter  was  at  first  produced  by  treating 
aniline  with  anhydrous  chlorides.  Thus,  A.  W.  Hofmann 
obtained  a  red  colour  from  aniline  by  treating  one  part  by 
volume  of  bichloride  of  carbon  (CC12)  with  three  parts  of 
aniline,  at  1700  to  1800  C,  in  a  sealed  tube  for  the  space  of 
30  hours ;  a  blackish  mass  was  thus  produced.  Treated 
with  water  this  substance  was  only  partly  dissolved,  a  con- 
siderable residue  remaining.  The  solution  yields  with  potash 
an  oil-like  precipitate  containing  much  unaltered  aniline. 
Freed  from  this  by  boiling  with  potash,  the  precipitate  is  trans- 
formed into  a  thick  oil  which  gradually  crystallises.  Upon 
washing  with  cold  alcohol,  and  crystallising  from  hot  alcohol, 
this  substance  becomes  quite  white,  whilst  the  solution  is 
of  a  bright  crimson  colour.  The  portion  of  the  above-men- 
tioned mass  insoluble  in  water  can  be  easily  dissolved  in 
hydrochloric  acid,  from  which  solution  alkalis  precipitate  a 
dirty  red  powder,  soluble  in  alcohol  with  a  crimson  colour. 

The  white  substance  is  said  to  have  the  formula  C38HI7N3 ; 
it  is  a  base  soluble  in  all  acids.  The  red  coloured  substance 
is  said  to  be  quite  different  from  common  magenta,  and  is 
usually  called  Hofmann's  red,  though  I  think  that  the  dif- 
ference between  this  substance  and  magenta  depends  only 
upon  an  unimportant  admixture. 

MM.  Mounet  and  Dury,  of  Lyons,*  have  produced  this  red 
colour  on  a  large  scale.    They  heat  one  part  of  bichloride 

*  Dingler's  Pol.  Journ.,  1861,  vol.  159,  p.  392, 


MAGENTA. 


35 


of  carbon  with  four  parts  of  aniline  in  a  copper  vessel  lined 
with  lead,  at  a  temperature  of  n6° — n8°  C.  To  complete  the 
operation  the  vessel  is  finally  heated  to  1700 — 1800  C. 

Instead  of  bichloride  of  carbon,  which  Hofmann  employed, 
M.  Natanson*  in  1856  used  chloride  of  elayl  to  obtain  a  red 
colour  from  aniline. 

On  the  8th  of  April,  1859,  a  patent  was  granted  to  MM. 
Renard  and  Franc,  of  Lyons,  for  a  method  of  obtaining 
magenta  from  aniline  by  means  of  bichloride  of  tin.  The  bi- 
chloride of  tin  employed  is  anhydrous,  and  is  usually  called 
spiritus  fumans  libavii.  This  substance  is  mixed  with  the 
aniline,  and  heated  from  15  to  20  minutes  to  1800 — 2000  C.  The 
mixture  becomes  at  first  yellow,  and  then  turns  dark  red. 
The  mass  thus  obtained  is  poured  while  still  warm  and  fluid 
into  water,  which  is  then  boiled.  All  the  undissolved  sub- 
stances are  then  allowed  to  precipitate,  and  the  liquid  is  fil- 
tered. The  solution  now  contains  a  hydrochlorate  and  a 
resinous  substance.  To  obtain  the  colour  pure  some  soluble 
salt  is  added  to  the  mixture,  whereby  the  colouring  matter  is 
precipitated,  as  magenta  is  very  difficultly  soluble  in  salt 
solutions. t  Common  salt,  nitrate  of  potash,  &c,  are  em- 
ployed for  this  purpose. 

To  separate  the  adhering  salts  the  precipitate  is  treated 
with  a  little  cold  water,  and  the  colour  is  then  dissolved  in 
hot  water  and  filtered.  On  cooling,  the  solution  yields  first 
a  resinous  precipitate,  and  then  the  colouring  matter,  which 
by  crystallisation  from  alcohol  can  be  obtained  in  small  plates 
of  a  greenish  metallic  lustre. 

The  patent  of  MM.  Renard  and  Franc  includes  not  only 
bichloride  of  tin,  but  generally  all  chlorides,  iodides,  bromides, 
and  fluorides  of  tin,  mercury,  and  iron,  together  with  the 
sulphates,  nitrates,  and  chlorates  of  these  metals.  Hence 
the  method  of  Mr.  R.  A.  Brooman  I  to  obtain  magenta  by 
treating  aniline  with  anhydrous  bichloride  of  mercury  or 
titanium,  or  with  bromide  or  iodide  of  tin,  is  already  included 

*  Annal.  d.  Chem.  u.  Pharm.,  1856,  vol.  98,  p.  291. 
f  We  shall  return  to  this  subjed  again. 
X  Rep.  of  Pat.  Inv.,  Aug.  i860,  p.  112. 

D  2 


36 


MAGENTA. 


in  the  terms  of  the  patent  of  Renard  and  Franc.  In  the 
same  way,  also,  crystallised  hydrated  bichloride  of  tin  can 
be  used  for  the  preparation  of  magenta. 

A  new  method  of  getting  the  red  colour  was  introduced  by 
M.  A.  Schlumberger,*  who  in  i860  employed  crystallised 
nitrate  of  the  protoxide  of  mercury  (Hg20,  N05  +  2HO). 
To  100  parts  of  aniline  he  added  60  parts  of  the  nitrate,  and 
heated  the  mixture  in  a  glass  retort  till  it  boiled.  Magenta 
can  be  extracted  from  the  resinous  mass  thus  obtained  by 
means  of  water,  a  brownish  violet  resin  being  left  as  a  residue. 

This  method  is  included  under  the  terms  of  the  patent 
granted  in  1859  to  Thomas  Perkin,  who  produced  an  aniline 
red  by  treating  aniline  with  neutral  or  basic  nitrate  of  the 
proto-  and  per-oxide  of  mercury,  sulphate  of  the  protoxide  of 
mercury,  and  the  nitrite  of  the  same  base.  10  parts  of 
aniline  were  employed  with  from  6  to  8  parts  of  the  basic 
nitrate  of  the  protoxide  of  mercury,  whereby  a  bluish  red 
paste  was  obtained,  metallic  mercury  falling  down  to  the 
bottom  of  the  vessel.  By  a  similar  process,  M.  Geber- Keller  t 
produced  magenta,  called  by  him  azaleine.  According  to 
the  specification  of  this  discoverer's  patent,  10  parts  of  aniline 
are  to  be  treated  with  7  parts  of  dry  powdered  nitrate  of 
peroxide  of  mercury.  The  heating  is  continued  from  8  to  9 
hours,  at  a  temperature  of  ioo°  to  1060  C.  Aniline  is  thus 
transformed  into  magenta,  while  the  mercury  falls  to  the 
bottom.  The  mass  thus  obtained  is  allowed  to  cool,  then 
boiled  with  water,  and  the  solution  allowed  to  crystallise. 
The  magenta  is  obtained  in  splendid  large  octohedra,  having 
a  bright  metallic  lustre  similar  to  that  of  the  wing  cases  of 
cantharides. 

This  method  of  obtaining  magenta  is  still  employed  ifi 
making  the  purest  aniline  red,  which  is  known  by  the  name 
of  rubine.  In  the  manufacture  of  this,  aniline  is  treated  with  a 
neutral  and  quite  concentrated  solution  of  nitrate  of  peroxide 
of  mercury,  for  from  10  to  18  hours,  at  a  temperature  of 
1200  C.    In  this  way  a  thick  red  liquid  is  formed,  mercury 

*  Dingler's  polyt.  Journ.,  vol.  157,  p.  2gz. 
f  Reprt.  d.  Chem.  Appl.,  i860,  ii.,  p.  52. 


MAGENTA. 


37 


sinking  to  the  bottom  of  the  vessel.  To  separate  the  excess 
of  aniline  from  this  liquid  (which  cannot  be  distilled  at  1200) 
the  whole  is  poured  into  an  iron  retort,  whence  the  aniline  is 
distilled  off  by  means  of  steam,  and  the  red  colour  formed  in 
the  above  operation  is  dissolved  in  the  water.  Common  salt 
or  sulphate  of  soda  is  then  added  to  the  solution,  whereupon, 
after  cooling,  crystals  of  magenta  are  deposited,  which  may 
be  purified  by  re-crystallisation. 

At  the  low  temperature  at  which  this  red  colour  is  formed, 
it  retains  all  its  splendour  and  brightness,  and  at  the  same 
time  a  much  smaller  quantity  of  the  resinous  substance  is 
produced.  Moreover,  the  mercury  being  quite  reduced,  and 
completely  separated  from  the  mass,  this  kind  of  magenta 
is  quite  free  from  poison,  and  may  be  used  by  confectioners. 
It  is  much  employed  in  dyeing  silk.  In  manufacturing  this 
colour,  I  observed  that  the  nitrate  of  mercury  must  be 
entirely  free  from  nitrous  acid,  which  is  formed  when  mercury 
is  dissolved  in  nitric  acid.  For  this  reason  it  is  better  not 
to  employ  direCtly  the  solution  of  mercury  in  nitric  acid,  but 
to  allow  the  solution  to  crystallise.  The  crystals  are  to  be 
collected,  dried,  and  stirred  in  a  porcelain  pan  over  an  open 
fire  until  all  the  nitrous  acid  and  excess  of  nitric  acid  are 
evaporated.  Then  the  crystals  are  again  dissolved  in  water, 
and  the  concentrated  solution  is  employed  to  manufacture 
magenta. 

The  phosphate  and  acetate  of  mercury  have  been  used  by 
Mr.  C.  G.  Williams,*  to  make  magenta.  The  same  chemist 
also  uses  arsenious  acid  for  this  purpose.  He  adds  to 
i  equivalent  of  hydrochlorate  of  aniline,  2  equivalents  of 
water,  and  a  mixture  of  3  equivalents  of  aniline  and  1  equiva- 
lent of  arsenious  acid.  The  colouring  matter  is  produced  on 
heating. 

Nitrate  of  lead  has  been  employed  to  make  an  aniline  red, 
by  MM.  Dale  and  Caro.t  Aniline  is  saturated  with  hydro- 
chloric acid  gas,  and  then  heated  for  ij  hours  in  an  oil  bath 
at  a  temperature  of  1900  C;   the  nitrate  of  lead  is  now 

*  London  Journ.  of  Arts,  Nov.  1863,  p.  268.  Dingler's  Poiyt.  Journ.,  170, 
442. 

f  English  Patent,  granted  May,  i860. 


38 


MAGENTA, 


added  as  a  dry  powder  with  constant  agitation.  The  colour- 
ing matter  thus  obtained  is  dissolved  in  boiling  water,  and 
precipitated  by  nitrate  of  soda,  common  salt  not  being 
adapted  to  this  purpose,  because  chloride  of  lead  is  almost 
insoluble  in  water. 

MM.  Depouilly  and  Lauth  oxidise  aniline  in  the  most 
direft  way.  They  use  instead  of  nitrates,  nitric  acid  itself. 
Their  patent  is  dated  June,  i860,  and  according  to  the  speci- 
fication nitrate  of  aniline  is  heated  to  2000  C.  To  prevent 
a  too  violent  reaction  of  the  nitric  acid  on  aniline  the 
latter  must  be  employed  in  excess. 

Mr.  E.  J.  Hughes,  whose  patent  is  dated  January,  i86o? 
heats  aniline  and  nitric  acid  directly  in  a  retort.  A  mixture 
of  32*5  parts  of  nitric  acid  of  specific  gravity  1*36,  and  100 
parts  of  aniline,  are  heated  in  a  retort  to  1500  or  2000  C.  All 
the  water  of  the  nitric  acid  being  distilled  off,  the  residue  in 
the  retort  is  boiled  one  hour,  whereby  a  thick  dark  red  syrup- 
like mass  is  obtained.  The  substance  is  then  treated  with 
a  solution  of  carbonate  of  soda  until  it  is  quite  neutral ;  20 
parts  of  pure  water  are  boiled,  and  1  part  of  the  mass 
thus  obtained  is  added  ;  the  heating  is  then  continued  until 
all  the  resin  has  risen  to  the  top  and  is  taken  off.  By  filter- 
ing and  allowing  to  cool,  the  solution  yields  a  red  coloured 
mass  having  a  metallic  green  reflection,  which  is  ground 
and  sold  diredt. 

Mr.  Blackley,  and  afterwards  Mr.  Watson,  have  proved 
that  it  is  possible  to  obtain  magenta  as  a  violet  and  blue 
colour  by  treating  aniline  with  aqua  regia  (chloro-nitrous 
acid,  N02C1). 

None  of  the  methods  we  have  hitherto  spoken  of  are  now 
employed  in  practice,  having  been  superseded  by  a  method 
that  especially  excels  in  the  cheapness  of  the  materials  used 
in  the  reactions.  The  process  of  preparing  magenta  by 
means  of  nitrate  of  mercury  is,  however,  still  used  in  some 
cases,  but  its  employment  is  very  limited,  and  I  know  only 
two  manufactories  where  it  is  practically  effected. 

Magenta  is  now  only  made  by  treating  aniline  with  arsenic 
acid  (As05).     In  January,  i860,  an  English  patent  was 


MAGENTA. 


39 


granted  to  Mr.  H.  Medlock  for  obtaining  magenta,  as 
follows: — 2  parts  of  aniline  are  mixed  with  i  part  of 
dry  arsenic  acid,  and  left  either  at  common  tempe- 
rature or  the  boiling  point  of  aniline,  until  the  mixture 
has  acquired  a  deep  purple  colour.  The  solution  of  this 
mass  in  water  is  filtered,  whereupon  a  purple  tarry  colouring 
matter  is  left  on  the  filter,  which  can  be  dissolved  by  treating 
with  alcohol.  This  patent  specification  has  the  same 
peculiarity  common  to  a  thousand  others :  it  cannot  be 
carried  out  in  practice.  We  shall  show  hereafter  that  only 
a  solution  of  arsenic  acid  is  able  to  transform  aniline  into 
magenta.  Moreover,  the  method  of  purifying  the  mass  ob- 
tained is  wholly  insufficient,  so  that  it  is  impossible  to  get  a 
useful  colour  by  following  Mr.  Medlock's  patent  specification. 

A  second  patent,  for  France,  founded  on  the  employment 
of  arsenic  acid,  was  granted  to  MM.  C.  Girard  and  G.  de 
Laire,*  in  Paris. 

A  solution  of  12  parts  of  arsenic  acid  in  12  parts  of  water, 
is  mixed  with  10  parts  of  aniline  oil  and  raised  to  1200  C.  At 
the  end  of  the  operation  the  temperature  is  raised  to  1600  C, 
which  degree  must  be  never  exceeded.  After  from  4  to  5 
hours  the  operation  is  finished.  Thus  a  homogeneous  mass 
is  formed,  which  liquefies  under  ioo°  C.  Allowed  to  cool, 
this  solidifies  and  takes  a  bright  metallic  lustre.  It  is  easily 
soluble  in  water,  the  colour  of  the  solution  being  red. 

These  are  the  principles  on  which  the  manufacture  of 
aniline  red  or  magenta  is  founded.  The  employment  of 
arsenic  acid  and  aniline  is  the  same  throughout  ;  the  sub- 
sequent treatment  alone  being  variable. 

We  will  describe  here  the  apparatus  used  for  making 
magenta.  For  the  purpose  of  treating  aniline  oil  and  arsenic 
acid  dissolved  in  water,  a  vessel  is  used  of  the  form  of  an 
iron  pot,  enamelled  in  the  inside,  and  closed  with  a  lid, 
through  which  an  iron  agitator  reaches  into  the  apparatus. 
In  the  lid  is  also  an  opening  through  which  a  thermometer 
may  be  introduced  into  the  liquefied  mass,  and  another 

*  Dingler's  Polyt.  Journ,,  vol.  159,  p.  229,  452. 


40 


MAGENTA. 


closed  with  a  wooden  stopper  through  which  the  progress  of 
the  operation  may  be  observed.  A  third  opening  in  the  lid 
admits  an  iron  tube  bent  at  a  right  angle,  which  can  be 
joined  by  an  india-rubber  tube  to  a  condensing  apparatus,  so 
as  to  collect  the  aniline  which  is  vapourised  during  the 

Fig.  6. 


operation.  The  lid  is  movable,  fastened  with  screws,  and 
tightened  with  a  lead  washer.  The  whole  apparatus,  the 
capacity  of  which  varies  according  to  the  quantities  dealt 
with,  is  surrounded  with  another  pot  of  the  same  form,  and 
the  latter  is  filled  with  glycerin  or  paraffin.  A  thermo- 
meter is  also  put  in  the  surrounding  vessel  to  observe  the 
temperature  there.  The  second  vessel  is  heated  over  an 
open  fire,  and  serves  only  as  an  oil  bath. 

The  inner  vessel  is  filled  with  100  parts  of  aniline  oil,  and 
150  to  200  parts  of  a  solution  of  arsenic  acid,  containing  75 
per  cent  of  the  dry  acid.  After  removing  the  lid  of  the 
vessel,  aniline  oil  is  first  poured  in,  then  the  dissolved 
arsenic  acid  is  gradually  added.  As  soon  as  aniline  and 
arsenic  acid  are  mixed,  heat  is  produced,  and  a  white  or 
reddish  mass  is  formed  consisting  of  arseniate  of  aniline. 
When  all  the  arsenic  acid  has  been  added,  the  lid  is  fastened 
down  and  the  agitator  is  moved.  The  oil  bath  is 
heated,  and  the  arseniate  of  aniline  now  liquefies  and 
assumes  a  reddish  colour.    The  heat  is  then  raised  to  1800  C, 


MAGENTA. 


41 


the  temperature  at  which  aniline  oil  begins  to  boil.  (Of 
course  the  thermometer  in  the  outward  vessel  must  stand  at 
about  1850  in  order  that  the  inner  vessel  may  be  at  1800.) 
Aniline  and  water  now  distil  through  the  bent  pipe  into  the 
condensing  tube,  and  are  collected  in  a  receiver.  The  mass 
in  the  vessel  gradually  becomes  thicker,  and  finally  so  thick 
that  the  agitator  can  only  be  moved  with  difficulty.  From 
time  to  time  an  iron  rod  is  introduced,  by  removing  the 
wooden  stopper  from  the  hole  in  the  lid.  The  small  portion 
of  the  mass  adhering  to  the  rod  is  removed  and  allowed  to 
cool ;  if  its  colour  after  cooling  is  of  a  pure  metallic  bronze, 
the  mass  is  fit  for  use.  If  the  colour  is  still  blackish  the 
mass  must  be  left  some  time  longer  in  the  vessel. 

During  the  whole  operation  the  agitator  must  be  con- 
stantly turned  to  prevent  the  contents  from  adhering  to  the 
walls  of  the  vessel.  When  the  mass  is  ready  it  is  taken  out 
of  the  vessel  by  means  of  a  large  iron  spoon.  The  workmen 
employed  in  this  work  must  guard  against  the  poisonous 
vapours,  by  binding  a  cloth  over  the  mouth  and  nose.  The 
liquid  mass  is  put  into  a  wooden  box  lined  with  paper,  where 
it  is  allowed  to  cool.  After  cooling,  the  mass  takes  a 
greenish  metallic  lustre,  which  is  brighter  as  the  operation 
is  more  successful.  It  finally  becomes  so  hard  as  to 
require  to  be  broken  with  a  hammer  into  small  pieces. 

We  have  before  shown  that  by  mixing  aniline  with  a 
solution  of  arsenic  acid,  arseniate  of  aniline  is  formed,  but 
by  heating,  this  is  again  transformed  into  another  substance. 
The  arsenic  acid  oxidises  the  mixture  of  aniline  and  toluidine 
contained  in  the  aniline  oil,  to  a  red  substance  called  by 
chemists  rosaniline,  being  transformed  and  becoming 
arsenious  acid  (As03),  so  that  we  may  represent  the  whole 
process  which  takes  place  in  the  vessel  by  the  formula — 

3(CI4H9N)  +  ( C^N)  +  3AsO^  = 

Toluidine.  Aniline.  Arsenic 

acid. 

=  C40HI9N3  +  3ASO3  +  6HO. 

Rosaniline.  Arsenious 
acid. 


42 


MAGENTA. 


The  basic  rosaniline  combines  with  the  excess  of  arsenic 
acid  contained  in  the  mass,  and  forms  arseniate  of  rosaniline. 
The  excess  of  aniline  oil  and  the  water  from  the  solution  of 
arsenic  acid,  together  with  that  formed  during  the  process, 
volatilise  and  are  collected  in  the  receiver. 

In  this  operation  not  only  rosaniline — the  basis  of  magenta 
— but  also  a  number  of  other  basic  substances  are  formed,  of 
which  we  shall  speak  hereafter.  It  is  therefore  impossible 
for  the  transformation  of  aniline  into  rosaniline  to  be  as 
simple  as  represented  by  Hofmann  in  the  formula  given 
above* 

The  time  occupied  in  the  operation  is  not  always  the 
same.  It  depends  on  whether  the  aniline  oil  contains  an 
excess  of  toluidine  or  of  aniline.  In  the  former  case  the  pro- 
cess will  fesf  longer  than  in  the  latter.  The  aniline  oil  best 
for  making  magenta  is,  as  above  mentioned,  that  containing 
75  per  cent  kuphaniline  and  25  per  cent  baraniline.  All  other 
mixtures  will  yield  rosaniline,  but  not  so  quickly  or  of  so 
good  a  quality. 

The  molten  mass  produced  as  above  mentioned  is  broken 
into  pieces  with  a  hammer  and  heated  with  boiling  water. 
This  was  formerly  effected  by  putting  the  pieces  into  a  vat 
and  pouring  water  on  them,  steam  being  introduced  through 
a  tube  to  cause  the  water  to  boil.  The  boiling  water 
dissolves  the  red  base  combined  with  arsenic  acid,  a 
brown  tarry  mass  remaining.  In  order  to  dissolve  out  all 
the  red  colour  included  in  the  tarry  mass,  the  crude  colour, 
liquefied  by  the  heat  of  boiling  water,  must  be  well  stirred 
up  with  poles  by  the  workmen.  When  the  water  is 
saturated  with  the  colour  it  must  be  drawn  off  and  filtered, 
fresh  water  being  poured  on  to  the  molten  mass  until  no 
more  red  is  contained  therein,  and  the  solutions  must  be 
filtered  to  separate  the  portions  of  resinous  substances 
mechanically  mixed  with  them.  For  this  purpose  a  filter 
of  felt  or  cloth  was  formerly  employed,  but  this  being  soon 
obstructed  by  the  resinous  mass,  an  immense  quantity  of 
filtering  material  was  necessary  to  filter  an  inconsiderable 
quantity  of  the  solution.    The  solution  also  was  formerly 


MAGENTA. 


43 


ladled  from  the  vats  into  the  filters.  This  caused  much  to 
be  spilt,  so  that  the  floor  of  the  manufactory  was  always 
covered  with  the  red  fluid. 

All  these  inconveniences  may  be  prevented  by  using  the 
apparatus  now  about  to  be  described.  It  is  not  yet  generally 
known,  and  in  many  manufactories  they  still  work  by  the 
old  imperfeft  method. 

The  molten  mass  is  put  into  a  boiler,  such  as  is  used  for 
steam  engines.  This  boiler,  of  a  simple  cylindrical  form, 
bears  a  shaft  turning  in  the  middle  of  the  boiler  by  means  of 

Fig.  7.  ^f£^K&7>' 


suitably  arranged  machinery.  The  shaft  carries  iron  paddles 
on  every  side,  which  when  it  turns,  work  in  the  liquefied 
mass.  Upon  this,  water  is  poured  through  a  tube  and  is 
heated  by  steam  introduced  through  another  tube  which 
reaches  almost  to  the  bottom  of  the  boiler. 

While  the  water  boils  the  temperature  is  kept  up  by  the 
introduction  of  fresh  steam,  and  the  claws  work  upon  the 
colour  mass,  causing  every  portion  of  it  to  come  into 
contact  with  the  boiling  water.  When  this  is  saturated,  it 
must  be  drawn  off  and  filtered,  which  two  operations  are  thus 
effected  at  once.    A  tube  reaches  almost  to  the  bottom  of  the 


44 


MAGENTA. 


boiler,  and  the  tap  being  opened,  the  solution  is  forced  by 
means  of  steam  through  this  tube,  and  led  by  it  into  the 
crystallising  vats.  As  it  leaves  the  boiler  the  solution  is 
made  to  pass  through  a  filter.  This  consists  of  two  shell- 
shaped  iron  vessels  screwed  closely  together.  Between  them 
is  a  felt  plate  through  which  the  solution  is  pressed  by  means 
of  steam  from  below  upwards.  The  resinous  substances  in 
the  solution  cannot  pass  the  felt,  and  are  retained  at  its  sur- 
face, but  being  hot  they  drop  down  again  into  the  boiler  and 
do  not  clog  the  filter.  When  one  filter  is  clogged  another 
can  be  substituted  by  closing  one  and  opening  the  other  tap. 
The  filter  is  then  taken  out,  and  the  felt  cleaned  or  replaced 
by  a  fresh  piece. 

Thus,  without  any  inconvenience,  the  solution  of  aniline  red 
is  brought  to  any  part  of  the  manufactory,  and  filtered  at  the 
same  time,  all  waste  of  the  red  liquid  being  entirely  pre- 
vented. The  solution  when  put  into  the  crystallising  vats  is 
mixed  with  from  2  to  4  per  cent  of  common  salt,  for  two  pur- 
poses : — First,  to  transform  the  arseniate  of  the  red  base  into 
the  hydrochlorate,  then  to  precipitate  this  hydrochlorate, 
the  salts  of  the  red  base  being  difficultly  soluble  in  solutions 
of  other  salts.  After  two  or  three  days  the  walls  of  the  vat 
are  found  covered  with  crystals  of  magenta,  whereupon  the 
solution  is  drawn  off  and  employed,  instead  of  a  fresh  supply 
of  water,  to  extract  another  quantity  of  crude  magenta  mass. 

The  crystals  obtained,  as  above  described,  are  re-dissolved 
in  pure  water  to  form  a  hot  concentrated  solution,  and  treated 
once  more  with  common  salt.  A  purer  magenta  is  now  ob- 
tained, which,  after  crystallisation  for  the  third  time,  will  be 
found  quite  pure  and  of  a  splendid  shade. 

In  high  vats  larger  crystals  are  obtained  than  in  low 
vessels.  Very  large  crystals  are  also  obtained  by  allowing 
the  liquid  to  cool  very  slowly,  and  also  by  using  sulphate  of 
soda  in  the  place  of  common  salt.  Then  the  sulphates  of  the 
red  bases  are  formed,  which  produces  larger  crystals  con- 
taining a  smaller  proportion  of  the  base  than  those  of  the 
hydrochlorate.  Such  large  crystals  are  sometimes  produced, 
and  are  usually  sold  under  the  name  of  Diamond  Magenta. 


MAGENTA. 


45 


The  remaining  solutions  contain  arseniate  and  arsenite  of 
soda,  and  are  therefore  exceedingly  poisonous.  To  free  them 
from  arsenic  they  are  mixed  with  milk  of  lime,  whereby 
arseniate  and  arsenite  of  lime  are  precipitated,  together  with 
a  little  colouring  matter  still  contained  in  the  solution.  It 
is,  however,  best  to  evaporate  the  whole  solution  in  large 
iron  pans  under  a  chimney  with  a  strong  draught,  whereby 
the  arseniate  of  soda  is  obtained  in  beautiful  crystals,  which 
may  be  used  in  calico  printing,  &c. 

A  larger  quantity  of  magenta  may  be  obtained  from  the 
solutions  by  adding  crystals  of  soda  when  magenta  ceases  to 
be  produced  by  evaporation.  A  considerable  additional  quan- 
tity of  colouring  matter  may  thus  be  obtained,  which  is  re- 
dissolved  and  added  to  any  crystallising  solution. 

In  a  well  conduced  operation  34  lbs.  of  magenta  may  be 
produced  from  one  to  two  cwts.  of  aniline  oil,  provided  that 
the  aniline  oil  used  is  of  suitable  composition. 

Formerly  the  crude  red  colour  mass  was  extracted  by 
dilute  hydrochloric  acid,  and  then  precipitated  by  carbonate 
of  soda  or  caustic  soda.  This  method,  however,  was  found 
in  practice  so  inconvenient  that  it  has  been  entirely  aban- 
doned. 

In  i860  Mr.  R.  Smith,  of  Glasgow,  took  out  a  patent  for 
the  transformation  of  aniline  oil  into  magenta.  The  opera- 
tion described  by  Mr.  Smith*  is  very  long  and  inconvenient, 
and,  what  is  worse,  useful  magenta  cannot  be  obtained  by 
this  method  ;  it  is  therefore  of  no  value. 

Nitrate  of  antimony  (2Sb03,  N05)  has  even  been  used  for 
making  magenta.  Mr.  Gratrix  mixes  five  parts  of  aniline 
oil  with  four  parts  of  the  nitrate  (got  by  adding  fuming 
nitric  acid  to  protoxide  of  antimony)  and  heats  the  mixture 
to  820  C. ;  the  liquid  part  of  the  mass  is  then  separated  and 
heated  for  ten  minutes  to  1770  C.  The  red  colour  thus  ob- 
tained is  extracted  in  the  usual  manner. 

In  this  method  the  antimony  does  not  seem  to  be  of  any 
importance.    Its  nitrate  being  a  very  weak  compound,  the 


*  Polyt.  Centrabl.,  1864,  p.  754. 


46 


MAGENTA. 


protoxide  is  immediately  set  free,  and  the  nitric  acid  trans- 
forms the  aniline  oil  into  magenta.  Even  water  when  added 
to  the  nitrate  of  antimony  decomposes  it ;  this  operation  is, 
therefore,  in  fac5t  identical  with  that  of  Mr.  E.  J.  Hughes, 
mentioned  above. 

To  complete  these  remarks  we  will  still  mention  some 
methods  of  transforming  aniline  into  magenta,  which  are  of 
no  importance  in  practice. 

Bran,  flour,  saw-dust,  &c,  distilled  with  half  their 
weight  of  sulphuric  acid  and  the  same  quantity  of  water, 
yield  an  acidulous  distillate,  which,  after  saturation  with 
potash  and  re-distillation,  yields  water  and  a  few  drops  of  an 
oil  which  can  be  separated  by  chloride  of  calcium. 

This  oil  is  called  furfurol.  Its  empiric  formula  is  CIOH404. 
It  is  colourless,  becomes  brown  by  exposure  to  the  air,  and 
boils  at  1630  C.  It  is  soluble  in  water,  spirits,  and  ether. 
Mr.  Stenhouse*  obtained  a  beautiful  red  colour  by  treating 
aniline  with  the  above-mentioned  furfurol.  He  isolated  the 
red  colouring  matter  by  allowing  the  solution  of  acetate  of 
aniline  and  furfurol  to  stand  at  rest. 

A  pitch-like  substance  covers  the  walls  of  the  vessel,  the 
solution  becoming  colourless.  This  pitch-like  substance  is 
the  pure  colouring  matter,  and  has  a  surface  lustre  similar 
to  that  of  the  wing  scales  of  cantharides.  It  is  insoluble  in 
water,  and  may  be  dissolved  in  spirits,  methyl  alcohol,  and 
acetic  acid.  Wool  and  silk  dyed  with  this  substance  to  a 
red  shade  similar  to  magenta  are,  however,  bleached  again 
after  a  few  hours'  exposure  to  the  air,  even  if  the  dyed  sub- 
stances are  not  submitted  to  the  influence  of  light. 

The  method  of  making  magenta  invented  by  M.  F.  Folt 
is  very  interesting.  This  chemist  uses  the  oxygen  of  indigo, 
which  is  transformed  by  every  reducing  agent  into  white 
indigo. 

M.  Koechlint  prepares  a  substance  similar  to  magenta  by 
treating  aniline  oil  with  crude  wood  vinegar,  or  wood  tar. 

*  Repert  de  Chimie  Appl.,  ii.,  p.  220. 

f  Ibid.,  1892.    Dingler's  Polyt.  Journ.,  165,  397. 

X  Ibid.,  Sept.,  June,  1859,  p.  404. 


MAGENTA. 


47 


Here  the  empyreuma  of  these  substances  undoubtedly  pro- 
duces the  effeft. 

In  i860,  Mr.  Smith  showed  that  magenta  might  be  formed 
by  heating  aniline  oil  with  iodine  or  iodide  of  mercury. 

G.  Delvaux  heats  a  mixture  of  one  equivalent  of  aniline 
with  one  equivalent  of  the  hydrochlorate  of  aniline  for  from 
six  to  eight  hours,  at  a  temperature  of  about  1500  C.  A 
certain  quantity  of  magenta  is  thereby  formed,  which  may 
be  extracted  by  means  of  water.  To  simplify  the  process 
two  equivalents  of  aniline  and  one  equivalent  of  hydro- 
chloric acid  may  be  used.  Magenta  is  then  obtained  by 
heating  and  evaporating  the  water  from  the  solution. 

Every  aniline  salt  yields  magenta  when  heated  with  pure 
aniline  to  1500  C.  Sulphate  of  aniline  heated  to  2000  C,  turns 
to  a  violet  black,  and  then  yields,  when  treated  with  water, 
a  solution  of  magenta.  In  a  similar  manner,  hydrochlorate 
of  aniline  is  transformed  into  a  red  colour,  by  heating  it 
dry  and  mixed  with  sand  or  fluor  spar,  for  three  hours  to  a 
temperature  of  1800  C. 

To  produce  magenta  in  this  manner  on  a  large  scale, 
according  to  M.  Delvaux,  one  equivalent  of  hydrochlorate 
of  aniline  is  mixed  with  tenfold  its  weight  of  sand,  and  one 
equivalent  of  aniline.  After  agitation,  the  mixture  is  heated 
for  fifteen  hours,  at  from  no°  to  1200  C,  or  five  to  six  hours 
to  1500,  or  two  to  three  hours  to  1800.  The  mass  so  treated 
is  then  put  into  boiling  water,  by  which  a  large  quantity  of 
the  red  colour  is  dissolved  out. 

Theoretical  Observations  on  Magenta. 

The  investigations  into  the  theoretical  composition  of 
magenta  arose  out  of  a  patent  suit  between  the  discoverer 
of  azaleine,  Geber- Keller,  and  the  firm  Renard  and  Franc, 
of  Lyons,  the  manufacturers  of  the  so-called  fuchsine. 

In  this  suit  the  authorities  on  the  subject  of  the  chemistry 
of  colours  gave  their  judgments  ;  these  were  very  different, 
and  have  now  only  an  historical  interest ;  none  of  the  pro- 


48 


MAGENTA. 


posed  views  of  the  composition  of  magenta  possessed  any 
probability.  This  was  owing  to  the  faft  that  the  investiga- 
tions had  hitherto  been  made  upon  impure  magenta,  while 
no  one  suspected  the  presence  of  any  impurity.  Thus 
M.  A.  Bechamp,*  MM.  Persoz,  de  Luynes  and  Salvetat,t 
MM.  Bolley,  Guignet,  Geber-Keller,  Williams,  Schulz, 
Kopp,t  Jacquemin,  and  others  investigated  magenta,  and 
deduced  formulae  entirely  differing  among  themselves. 

Finally,  Dr.  Hofmann  settled  the  composition  of  magenta 
through  his  classical  investigations  upon  rosaniline.  Dr. 
Hofmann  ||  has  proved  that  the  cause  of  the  different  results 
obtained  by  the  above  named  chemists,  is  that  they  worked 
with  impure  products,  and  he  comes  to  the  conclusion  that 
the  two  colouring  matters,  which  caused  so  much  investiga- 
tion, had  only  an  inconsiderable  difference,  the  azaleine  of 
M.  Geber-Keller  being  the  nitrate,  and  the  so-called  fuchsine 
of  MM.  Renard  and  Franc  the  hydrochlorate  of  the  same 
base,  called  by  Hofmann  rosaniline. 

In  his  investigations,  Dr.  Hofmann  used  materials  supplied 
him  by  the  great  London  firm,  Messrs.  Simpson,  Maule,  and 
Nicholson,  who  sold  magenta  under  the  name  of  roseine. 
He  found  that  this  colouring  matter  was  the  acetate  of  an 
organic  base,  which  he  called  rosaniline.  The  boiling 
aqueous  solution  of  this  salt  yielded,  when  mixed  with 
ammonia,  a  crystalline  precipitate  of  a  reddish  colour,  which 
was  the  new  base  in  a  tolerably  pure  state.  The  solution 
separated  by  filtering  this  precipitate  contains  the  base  in 
a  still  greater  state  of  purity ;  it  may  be  obtained  by  allow- 
ing the  filtered  solution  to  cool.  The  perfectly  pure  base  is 
thus  obtained  in  the  form  of  colourless  crystalline  needles 
and  plates.  But  the  solubility  of  this  substance  in  ammoni- 
acal  water  is  so  slight,  that  only  small  quantities  can  be 
thus  obtained.  It  is  more  easily  soluble  in  alcohol,  which 
it  colours  red,  but  is  quite  insoluble  in  ether.  In  the  atmo- 
sphere the  base  turns  at  first  reddish,  and  finally  dark  red. 

*  Dingler's  Polyt.  Journ.,  vol.  156,  p.  309. 

f  DlNGLER,  VOl.  159,  p.  221. 

t  Chem.  Centralbl.,  1861,  No.  34. 

||   DlNGLER,  VOl.  165,  p.  60. 


MAGENTA. 


49 


This  variation  of  colour  is  said  to  be  unaccompanied  by  a 
variation  in  weight. 

At  ioo°  C.  rosaniline  quickly  loses  a  small  quantity  of 
adhering  water ;  the  heat  may  then  be  continued  up  to 
1300  without  any  variation  in  weight. 

At  a  high  temperature  the  base  is  decomposed,  a  coke-like 
mass  remaining,  and  an  oil  distilling  which  consists  princi- 
pally of  aniline.  According  to  his  analysis  Dr.  Hofmann 
thought  that  the  formula  of  rosaniline  was  C40H2IN302,  which 
he  changed  after  analysing  the  salts  of  the  base  into 

C40HI9N3,2HO. 

Rosaniline  is  a  well  characterised  base  yielding  several  series 
of  readily  crystallised  salts.  Dr.  Hofmann  finds  that  it 
forms  three  series  of  salts,  the  hydrochlorates  being  of  the 
formulae — 

C40HI9N3,  HC1. 
C40HI9N3,  2HCI. 
C40HI9N3,  3HCI. 

The  salts  containing  one  equivalent  of  acid  and  base  are 
most  easily  formed,  and  may  be  obtained  again  on  recrystal- 
lisation.  Those  containing  three  equivalents  of  the  acid 
are  decomposed  both  by  water  and  by  a  temperature  of 
ioo°  C. 

The  several  salts  of  this  colour  base  may  be  obtained  by 
direct  addition  of  the  proper  proportion  of  acid.  The  salts 
containing  one.  equivalent  of  acid  exhibit  by  reflected  light 
a  bright  metallic  lustre,  similar  to  that  of  the  wing  covers 
of  cantharides.  In  transmitted  light  they  appear  red,  and 
when  in  thick  layers  are  opaque. 

The  salts  containing  three  equivalents  of  acid  are  of  a 
yellowish  brown  colour,  both  in  a  solid  form  and  when 
dissolved.  They  are  more  soluble  than  those  with  one 
equivalent  of  the  acid.  Both  series  of  salts  crystallise 
easily. 

The  hydrochlorate  of  rosaniline, C40HI9N3,  HC1,  is  obtained 
from  its  boiling  solution  in  well  characterised  starlike  rhombic 
plates.  It  is  difficultly  soluble  in  water,  more  easily  in 
alcohol,  and  insoluble  in  ether. 

At  1300  C,  it  gives  off  all  accompanying  water.    At  100" 

E 


5° 


MAGENTA. 


it  retains  a  little,  and,  like  most  rosaniline  salts,  is  very 
hygroscopic.  It  is  more  soluble  in  dilute  hydrochloric  acid 
than  in  water.  The  moderately  heated  solution  of  the 
hydrochlorate  of  rosaniline,  when  mixed  with  concentrated 
hydrochloric  acid,  solidifies  on  cooling  to  a  magma  of  bright 
brown  needles,  which  when  washed  with  concentrated 
hydrochloric  acid,  and  dried  in  vacuo  over  sulphuric  acid, 
have  the  formula  C40HI9N3,  3HCI. 

At  ioo°  C.  this  hydrochlorate  gradually  loses  its  acid,  and 
turns  indigo-blue ;  upon  continuing  the  heat  of  ioo°  the 
colour  becomes  red,  and  the  salt  is  re-transformed  into  the 
hydrochlorate  with  one  equivalent  of  acid.  It  is  probable 
that  the  change  of  colour  into  blue  is  due  to  the  formation 
of  a  hydrochlorate  containing  two  equivalents  of  acid. 

Both  the  hydrochlorates  investigated  by  Dr.  Hofmann 
combine  with  chloride  of  platinum  to  form  double  salts,  the 
composition  of  which  is  said  to  answer  to  the  formulae — 

C40HI9N3,  HC1  +  PtCla, 
C40HI9N3,  3HCI  +  3PtCl2. 

The  hydrobromate  of  rosaniline  is  in  all  respedts  similar 
to  the  hydrochlorate,  but  is  still  less  soluble.  When  dried 
.at  1300  it  has  the  composition  C40HI9N3,  HBr. 

The  sulphate  of  rosaniline  is  obtained  by  dissolving  the 
pure  base  in  dilute  sulphuric  acid.  When  the  solution  cools, 
crystals  of  a  salt  are  formed,  which  has  the  formula — 
C40HI9N3,  HO  S03. 

This  salt  is  with  difficulty  soluble  in  water,  more  easily 
in  alcohol,  but  is  quite  insoluble  in  ether.  There  is  also 
another  acid  sulphate  which  was  not  investigated. 

In  the  same  manner  the  oxalate  of  rosaniline  may  be 
obtained.    When  dried  at  ioo°  its  formula  is — 
C40HI9N3,  HO  C203  +  HO. 

It  is  very  difficult  to  free  this  salt  from  its  water  of  crys- 
tallisation, the  temperature  at  which  it  loses  its  water  being 
very  near  to  that  at  which  it  is  decomposed. 

The  acetate,  of  the  formula  C40HI9N3,  HO  C4H303,  is, 
according  to  Dr.  Hofmann,  the  most  beautiful  of  the  whole 
series.    Nicholson  obtained  it  in  crystals  half  an  inch  in 


MAGENTA. 


51 


thickness.  It  is  easily  soluble  both  in  water  and  in  alcohol, 
on  which  account  it  is  difficult  to  crystallise  it. 

The  formiate  is  similar  to  the  acetate. 

The  chromate  of  rosaniline  may  be  obtained  by  adding  a 
solution  of  bichromate  of  potash  to  the  acetate  of  rosani- 
line dissolved  in  water.  A  brick-red  precipitate  appears, 
which  is  transformed  by  boiling  water  into  a  green,  crystal- 
line, almost  insoluble  powder. 

The  picrate  crystallises  in  beautiful  red  needles,  which  are 
only  with  difficulty  soluble  in  water. 

Rosaniline  is  altered  by  reducing  agents,  especially  by 
hydrogen  and  hydrosulphuric  acid. 

A  solution  of  rosaniline  in  hydrochloric  acid  is  soon 
decolorised  on  the  addition  of  zinc.  The  liquid  then  con- 
tains, besides  chloride  of  zinc,  the  hydrochlorate  of  a  new 
base,  which  both  when  pure  and  when  combined  with  acids, 
is  quite  colourless.  This  base  Dr.  Hofmann  called  leukani- 
line.  It  was  obtained  from  commercial  magenta,  and  by 
repeated  purification  is  obtained  of  a  yellow  colour.  The 
pure  base,  though  quite  white,  easily  turns  reddish  on 
exposure  to  the  atmosphere.  It  is  scarcely  soluble  in  cold, 
but  somewhat  so  in  hot  water,  and  on  cooling  is  deposited 
by  the  solution  in  small  crystals.  Alcohol  dissolves  the  base 
abundantly,  but  ether  only  in  very  small  quantities.  The 
best  solvent  for  leukaniline  seems  to  be  a  solution  of  the 
hydrochlorate  of  leukaniline,  in  which  it  dissolves  in  large 
quantities,  and  can  be  obtained  again  in  the  form  of 
needles.  It  may  be  dried  in  vacuo  over  sulphuric  acid 
without  variation  of  colour.  When  heated  cautiously,  it  turns 
red,  and  liquefies  at  ioo°,  forming  a  dark  red  fluid,  which 
solidifies  on  cooling  to  a  mass  not  so  richly  coloured.  It  con- 
tains no  water,  and  answers  when  dried  at  ioo°  to  the  formula 
C40H2IN3.  This  formula  was  found  to  be  correft  by  the 
analysis  of  the  hydrochlorate,  chloro-platinate,  and  nitrate. 

The  hydrochlorate  may  be  obtained  as  follows  from  com- 
mon magenta : — 

The  magenta — hydrochlorate  of  rosaniline — is  transformed 
by  treating  it  with  hydrosulphate  of  ammonia,  as  above 
described  in  the  case  of  leukaniline.    The  yellow  mass  thus 

E  2 


5^ 


LEUKANILINE. 


obtained  is  powdered,  and  freed  by  means  of  water  from  the 
adhering  hydrosulphate  of  ammonia,  after  which  it  is  dis- 
solved in  diluted  hydrochloric  acid.  The  dark  brown  solu- 
tion thus  formed  yields,  when  mixed  with  concentrated 
hydrochloric  acid,  an  abundant  crystalline  precipitate,  brown 
or  yellow,  according  to  the  purity  of  the  magenta  employed. 
It  may  be  purified  by  washing  with  concentrated  hydro- 
chloric acid,  in  which  the  precipitate  is  almost  insoluble,  but 
in  most  cases  it  is  necessary  to  re-dissolve  and  re-precipitate 
it  as  above  described.  Before  adding  concentrated  hydro- 
chloric acid  for  the  last  time,  the  solution  is  heated  to  boil- 
ing, whereby  on  cooling  the  hydrochlorate  of  leukaniline 
crystallises  in  well  formed  rectangular  plates,  very  small, 
but  brilliantly  white.  By  re-crystallisation  in  water  the 
purifying  is  completed. 

The  hydrochlorate  thus  obtained,  contains  three  equiva- 
lents of  acid,  and  even  when  dried  in  vacuo,  two  equivalents 
of  water.    The  formula  is  C40H2IN3,  3HCI  +  2HO. 

It  cannot  be  completely  dried  in  the  atmosphere,  but  all 
the  water  may  be  separated  by  heating  the  salt  for  a  suffi- 
cient time  to  ioo°  C,  and  exposing  to  a  current  of  hydrogen. 
It  is  not  possible  to  obtain  compounds  containing  a  smaller 
proportion  of  acid  by  dissolving  pure  leukaniline  in  the  solu- 
tion of  the  hydrochlorate.  If  chloride  of  platinum  is  added 
to  a  moderately  concentrated  warm  solution  of  the  hydro- 
chlorate of  leukaniline,  the  liquid  yields,  on  cooling,  well- 
defined  bright  orange  prisms,  which  are  slightly  soluble  in 
cold,  but  decomposed  in  boiling  water.  When  dried  at 
ioo°  C.  they  still  contain  two  equivalents  of  water,  which 
may  be  driven  off  at  a  higher  temperature.  The  composi- 
tion of  the  platinum  compound  is — 

C40H2IN3,  3HCI  +  3PtCl2  +  2HO. 

The  nitrate  crystallises  in  well-defined  white  needles, 
soluble  in  water  and  alcohol,  insoluble  in  ether,  and  with 
difficulty  in  nitric  acid.  When  dried  in  vacuo,  they  have 
the  composition  C40H2IN3,  HO  N05  +  2HO  N05  +  2HO. 
The  water  of  crystallisation  cannot  be  separated,  as  the 
salt  decomposes  at  ioo°. 

Leukaniline  may  be  re-transformed  by  oxidising  agents 


CHRYSANILINE. 


53 


into  rosaniline.  The  two  bases  are  therefore  similar  to  blue 
and  white  indigo. 

As  to  the  formation  of  rosaniline  from  aniline  oil,  we  have 
no  precise  information.  It  is  only  hypothetical  to  say  that 
rosaniline  (C40HlgN3)  is  formed  by  the  addition  of  two  equi- 
valents of  toluidine  to  one  of  aniline,  six  equivalents  of 
hydrogen  being  oxidised  by  the  oxygen  of  the  arsenic 
acid  : — 

2i2fl^)  +  ^HtN  +  60  =  C40HI9N3  +  6H0. 

Toluidine.  Aniline.  Rosaniline. 

As  before  mentioned  in  the  chapter  on  Aniline,  the  aniline 
oil  best  for  manufacturing  magenta  is  composed  of  one  part 
of  toluidine  with  three  parts  of  aniline,  so  that  five  parts 
of  aniline  must  be  eliminated  if  one  part  of  aniline  com- 
bines with  two  parts  of  toluidine  to  form  rosaniline.  The 
formation  of  rosaniline,  however,  is  not  unconnected  with 
that  of  other  products.  We  have  shown  that  when  rosani- 
line is  manufactured,  the  above  mentioned  browrn  resinous 
substance  is  also  obtained.  From  these  Mr.  Ed.  C.  Nicholson 
extracted  a  new  base  of  a  yellow  colour,  which  Dr.  Hofmann* 
investigated.  It  is  a  fine  yellow  powder,  similar  to  chro- 
mate  of  lead,  scarcely  soluble  in  water,  but  easily  dissolved 
by  alcohol  and  ether.  It  is  a  well  characterised  organic 
base,  which,  forming  two  series  of  well  crystallised  salts, 
has  received  the  name  of  chrysaniline,  on  account  of  its 
yellow  colour.  For  analysis  the  base  precipitated  from  the 
mononitrate  was  employed.  After  dissolving  and  re-crystal- 
lising this  salt  six  times,  it  was  precipitated  by  ammonia, 
and  the  pure  base  thus  obtained  was  analysed.  When  dried 
at  ioo°  C.  its  formula  was  found  to  be  C40HI7N3,  and  this 
was  confirmed  by  the  analysis  of  several  of  its  salts.  As 
will  be  seen,  this  base  only  differs  from  rosaniline  by  the 
subtraction  of  two  equivalents  of  hydrogen. 

The  hydrochlorate  of  chrysaniline  is  easily  obtained  by 
adding  concentrated  hydrochloric  acid  to  a  solution  of  chrys- 
aniline in  dilute  hydrochloric  acid.    It  is  obtained  in  this 

*  Compt.  Rend.,  part  45,  p.  818 ;  Dingler's  Polyt.  Journ.,  168,  p.  133  ; 
Journ.  f.  Chem.  u.  Pharm.,  1863,  p.  33. 


54 


CHRYSANILINE. 


manner  as  a  scarlet  crystalline  precipitate,  consisting  of 
small  plates  very  soluble  in  water,  less  so  in  alcohol,  and 
quite  insoluble  in  ether.    The  formula  of  this  salt  is — 

C40HI7N3,  2HC1. 

It  sometimes  contains  water,  and  its  formula  is  then — 
C40HI7N3,  2HCI  +  2HO. 

When  heated  for  a  fortnight,  at  a  temperature  of  between 
1600  and  1800,  it  is  transformed  into  a  yellow  crystalline 
powder,  less  soluble  in  water,  which  has  the  formula — 

C40HI7N3,  HC1. 

The  nitrates  of  chrysaniline  crystallise  very  easily  in  ruby 
coloured  needles  insoluble  in  water.  The  other  salts  of 
chrysaniline  are  precipitated  on  the  addition  of  any  soluble 
nitrate,  so  that  chrysaniline  may  be  used  as  a  reagent  for 
nitric  acid.  When  dilute  nitric  acid  is  boiled  with  an  excess 
of  chrysaniline,  the  mono-nitrate  of  this  base  is  formed,  which 
when  the  liquid  cools  crystallises  in  needles.  Its  formula  is 
C40H17N3,  HO  N05.  By  adding  a  solution  of  this  salt  to 
cold  concentrated  nitric  acid  a  precipitate  is  formed  of  the 
formula  C40HI7N3,  HO  N05  +  HO  N05,  which  can  be  obtained 
in  well  formed  prisms.  By  re-crystallisation  from  water  it 
loses  its  excess  of  nitric  acid. 

The  very  soluble  sulphate  is  scarcely  crystallisable. 

Until  lately  it  was  not.  possible  to  reproduce  rosaniline 
from  chrysaniline.  Even  the  formation  and  constitution  of 
this  substance  have  only  recently  been  known. 

The  salts  of  this  base  are  used  as  an  orange  dye.* 

The  existence  of  this  base  plainly  shows  how  it  is  that 
magenta  is  sometimes  obtained  of  a  yellow  shade,  in  which 
case  a  portion  of  the  resinous  base  is  contained  in  the  red 
colour. 


*  See  Chapter  on  Aniline  Yellow. 


CHAPTER  V. 


ANILINE   BLUE   AND  VIOLET. 

Even  before  the  discovery  of  aniline  red,  violet  shades  were 
produced  by  treating  aniline  oil  with  certain  agents,  and  soon 
after  the  discovery  of  magenta  blue  shades  were  obtained. 

We  may  regard  the  violet,  with  the  exception  of  one  kind, 
to  be  an  intermediate  stage  of  the  formation  of  aniline  blue 
from  the  red  colouring  matter,  that  is  to  say,  as  an  aniline 
blue  the  formation  of  which  has  been  interrupted  before  the 
close  of  the  operation,  and  in  which  therefore  the  substitution 
about  to  be  described  has  been  only  incompletely  effected. 

It  is  indifferent  whether  we  treat  magenta  with  aniline  oil 
or  transform  aniline  oil  at  first  into  magenta,  and  then  form 
aniline  blue  or  violet  by  means  of  the  excess  of  aniline. 
Generally  it  may  be  said  that  blue  and  violet  are  formed  by 
treating  magenta  with  reducing  agents,  or  by  adding  oxidis- 
ing substances  to  aniline  oil.  Hence  it  is  as  well  to  speak 
of  the  violet  and  blue  in  the  same  chapter. 

All  methods  of  obtaining  violet  immediately  from  aniline 
oil  are  now  of  only  historical  interest.  We  shall  enumerate 
them  in  chronological  order,  but  occupy  ourselves  only  with 
those  that  are  really  in  use,  and  which  are  all  founded  upon 
the  production  of  violet  and  blue  from  magenta. 

A  violet,  the  first  of  all  the  aniline  colours,  was  discovered 
by  Messrs.  Perkin  and  Church.  They  took  out  an  English 
patent  in  1858  for  a  method  of  producing  a  violet  colour  by 


56 


ANILINE  BLUE  AND  VIOLET. 


heating  sulphate  of  aniline,  toluidine,  cumidine,  or  cymidine 
with  bichromate  of  potash.  A  solution  of  one  equivalent  of 
sulphate  of  aniline  is  mixed  with  one  equivalent  of  bichro- 
mate of  potash  dissolved  in  water,  agitated,  and  left  to  stand. 
A  precipitate  is  thereby  formed,  which  is  collected,  washed 
with  water  to  eliminate  the  sulphate  of  potash  formed  during 
the  process,  and  then  treated  with  fluid  hydrocarbons  to  dis- 
solve out  a  brown  resinous  substance  which  adheres  to  the 
colour.  The  mass  thus  treated  represents  the  colour,  which 
may  be  dissolved  in  alcohol  or  methyl  spirit,  and  used  at 
once  for  dyeing.  Another  method  of  purifying  this  colouring 
matter  was  proposed  by  M.  Wilm*  in  1861. 

It  was  soon  after  discovered  that  these  violets  were  strongly 
affedted  by  oxidising  agents,  such  as  chloric  acid,  chromates, 
bleaching  powder,  &c,  and  by  them  changed  to  a  blue  colour. 
Afting  on  this  discovery,  M.  H.  Koechlin,t  of  Glasgow,  suc- 
ceeded in  transforming  aniline  diredtly  into  the  blue  colour. 
He  heated  one  litre  of  aniline  with  1 J  to  2  litres  of  hydro- 
chloric acid  and  80  grammes  of  bichromate  of  potash,  at  the 
temperature  of  the  boiling  point  of  aniline.  He  then  satu- 
rated the  liquid  with  a  solution  of  hydrate  of  lime,  and  fil- 
tered. In  this  manner  was  obtained  a  blue  solution  having 
an  alkaline  reaction. 

M.  Fritschet  found  as  early  as  1843  that  aniline  could  be 
transformed  into  a  blue  colour  by  chlorate  of  potash. 

To  get  the  pure  colouring  matter  Dr.  Hofmann  proposes 
to  add  a  few  drops  of  chlorous  acid  (C103)  to  a  solution  of 
aniline  in  hydrochloric  acid,  whereby  a  blue  mass  is  produced. 

M.  BechampH  obtains  aniline  blue  by  treating  aniline 
with  chlorine  until  a  dark  brown  mass  is  formed,  which  he 
heats  successively  to  a  temperature  of  1800  and  2000  C, 
whereby  the  brown  mass  is  transformed  into  the  blue  colour. 
In  a  similar  manner  a  blue  colouring  matter  may  be  obtained 
by  mixing  a  solution  of  the  nitrate  of  aniline  in  water  with  pow- 
dered chlorate  of  potash,  and  adding  to  this  mixture  a  strong 

*  Chem.  Centralbl.,  1861,  No.  5,  p.  69. 

f  Rep.  d.  Chim.  App.,  i860,  p.  196. 

I  Erdmann's  Jour.  f.  prac.  Chem.,  1843,  vol.  28 ,  p.  202. 

||  Comptes  Rendus,  1861,  part  52,  p.  538. 


ANILINE  BLUE  AND  VIOLET. 


57 


acid,  such  as  hydrochloric,  nitric,  or  oxalic,  and  a  little 
sugar.  Eight  hours  afterwards  an  abundant  dark  precipitate 
may  be  observed,  which  is  collected,  washed  with  water  con- 
taining ammonia,  and  then  dried.  This  is  the  pure  blue ;  it 
possesses  considerable  dyeing  power. 

Crossley  obtains  a  solution  which  dyes  purple  immediately, 
by  cautiously  heating  an  alcoholic  solution  of  aniline  and 
bisulphide  of  carbon  with  nitric  acid.  At  the  same  time  a 
resinous  mass  is  formed  from  which  Crossley  obtains  a  yellow 
colouring  matter. 

According  to  Messrs.  Beale  and  Kirkham,  a  violet  maybe 
obtained  when  one  part  by  measure  of  an  aqueous  solution 
of  hydrochlorate  of  aniline  of  the  specific  gravity  of  I'oi  is 
mixed  with  the  same  quantity  of  acetic  acid  (containing  25 
per  cent  of  the  anhydrous  acid),  and  there  is  added  gradually 
a  solution  of  bleaching  powder  of  the  specific  gravity  of  1*5 
(Beaume).  By  adding  the  solution  of  bleaching  powder  suc- 
cessively in  small  portions  every  shade  of  violet  is  easily  ob- 
tained, and  the  more  of  the  solution  that  is  used  the  bluer 
will  be  the  resulting  shade.  By  an  excess  of  bleaching 
powder  the  liquid  is  completely  decolorised.  A  violet  pre- 
cipitate is  formed,  which  is  collected  and  heated  with  an 
alkali  to  eliminate  the  adhering  resin.  The  violet  itself  is, 
like  every  aniline  violet,  quite  insoluble  in  alkalis. 

The  colouring  matter  when  prepared  is  dissolved  in  alcohol, 
and  on  evaporation  is  left  in  the  form  of  green  scales  of  a 
metallic  lustre.  The  same  result  may  be  obtained  by  using 
a  solution  of  chlorine  in  water.  Almost  the  same  method 
was  patented  in  England  by  Messrs.  Depouilly  and  Lauth 
in  June,  i860. 

Mr.  George  Phillips,  on  December  30th,  1863,  patented  a 
similar  method,  differing  from  the  former  only  by  moderating 
the  aftion  of  the  bleaching  powder.  He  produces  violet  by 
adding  300  parts  of  sulphate  of  iron  to  100  parts  of  sulphate 
of  aniline  and  40  parts  of  bleaching  powder.  The  mixture 
is  heated  at  ioo°  C.  until  the  desired  shade  is  obtained ;  the 
colour  thus  obtained  is  soluble  in  water,  and  maybe  obtained 
from  its  solution  by  precipitation  in  the  ordinary  manner. 


5§       Yi  '■■  V  "      ANILINE  BLUE  AND  VIOLET. 

Finally,^tKe  method  of  M.  B6champ*  is  interesting.  He 
obtained  a  beautiful  blue  colour  by  mixing  an  equal  number 
of  equivalents  of  aniline  and  of  phenic  acid  with  water,  and 
adding  to  this  mixture  an  aqueous  solution  of  bleaching 
powder. 

A  great  number  of  oxidising  agents  have  been  proposed 
for  the  transformation  of  aniline  into  blue  and  violet.  C.  G. 
Williams,  according  to  his  patent  of  1859,  mixes  a  solution 
of  100  parts  of  sulphate  of  aniline  with  a  solution  of  112  parts 
of  permanganate  of  potash.  He  then  heats  and  obtains  a 
precipitate  containing  a  violet  colouring  matter.  To  elimi- 
nate the  resin  the  precipitate  is  treated  with  benzol,  and  the 
colouring  matter  is  dissolved  in  alcohol.  Even  peroxide  of 
manganese  produces  a  violet  colour  when  an  acid  is  present. 
On  this  circumstance  is  founded  a  patent  dated  May,  1859, 
and  taken  out  by  Mr.  R.  D.  Kay.  Mr.  Pricet  substitutes 
oxide  of  lead  for  the  peroxide  of  manganese. 

According  to  a  patent  granted  May,  i860,  to  Messrs.  Dale 
and  Caro,  an  aqueous  solution  of  chloride  of  copper  produces 
a  violet  when  mixed  with  sulphate  of  aniline.  In  a  similar 
manner  Messrs.  Persoz,  de  Luynes,  and  Salvetat  produced  a 
blue  colour  by  heating  an  excess  of  aniline  in  a  sealed  tube 
with  chloride  of  tin.  This  product  was  formerly  sold  as 
Bleu  de  Paris.  The  same  result  may  be  obtained,  accord- 
ing to  Mr.  J.  J.  Coleman,  by  means  of  chloride  of  antimony. 
Mr.  Stadeler,  of  Zurich,  found  that  aniline  yielded  violet 
colours  when  heated  in  a  sealed  tube  with  azobenzol,  nitro- 
benzol,  hydroazobenzol,  &c. 

We  shall  now  proceed  to  describe  those  methods  which 
are  founded  on  the  principle  of  heating  aniline  red  or  ma- 
genta with  agents  which  transform  it  into  violet  or  blue  ;  in 
all  of  them  the  existence  of  magenta  is  pre-supposed. 

MM.  Schaffer  and  Gros-Renard  employed  a  solution  of 
shellac  in  any  alkali  to  transform  magenta  into  a  blue  colour- 
ing matter,  called  by  the  inventors  Bleu  de  Mulhouse.  Mr. 
E.  Kopp,t  who  describes  this  method,  says  that  a  solution 

*  Comp.  Rend.,  52,  538.    Dingler,  vol.  160,  p.  143. 
-f  Patent,  May,  1859. 

%  Examen  des  Matieres  color.    Saverne,  1861,  p.  90. 


ANILINE  BLUE  AND  VIOLET.         *lTfJy*$$  \ 

NX  /  p  ^  / 

of  shellac  produced  by  boiling  50  grammes  of  >wb$tja  §hellac 

with  18  grammes  of  soda  crystals  in  1  litre  of  water,*Ts  mixed 
with  50  grammes  of  a  solution  of  125  grammes  of  azaleine 
(magenta)  in  J  litre  of  alcohol  and  J  litre  of  water.  A  blue 
liquid  is  thus  obtained  the  colour  of  which  is  similar  to  that 
of  a  solution  of  the  ammonio-sulphate  of  copper.  By  using 
one  litre  of  water,  100  grammes  of  soda  crystals,  and  100 
grammes  of  the  azaleine  solution,  a  colour  called  Violet  de 
Mulhouse  is  obtained. 

By  treating  magenta  with  the  protochloride  of  tin,  M.  C. 
Lauth*  obtained  an  aniline  blue.  Violet  and  blue  shades 
may  also  be  got  by  adding  acid  salts  or  free  acids  to  a  solu- 
tion of  magenta  in  alcohol.  Instead  of  alcohol,  Mr.  E. 
Kopp  t  employs  methyl  alcohol.  A  blue  may  also  be  pro- 
duced much  more  easily  by  adding  aldehyd  to  a  solution  of 
magenta  in  dilute  sulphuric  acid.  In  this  process  the  alde- 
hyd is  transformed  into  acetic  acid,  which,  when  alcohol  is 
present,  combines  with  it  to  form  acetate  of  ethyl. 

The  most  important  method  of  transforming  aniline  red 
into  blue,  is  the  employment  of  aniline  oil  for  this  purpose. 
This  method  was  discovered  by  MM.  Girard  and  de  Laire; 
MM.  Persoz,  de  Luynes,  and  Salvetat  described  similar  pro- 
cesses some  time  afterwards.  The  patent  granted  to  MM. 
Girard  and  de  Laire  is  dated  24th  June,  1862,  and  its 
specification  is  as  follows  : — 

Magenta  purified  in  the  usual  manner  is  mixed  with  its 
own  weight  of  aniline,  and  the  mixture  is  heated  five  or  six 
hours,  at  a  temperature  of  from  1550  to  1850  C,  keeping  it  as 
near  as  possible  to  1650.  A  violet  substance  is  thereby 
obtained,  which  is  boiled  with  a  mixture  of  water  and 
hydrochloric  acid  until  it  is  entirely  purified.  For  one  part 
of  the  substance  ten  or  twelve  parts  of  hydrochloric  acid, 
diluted  with  the  same  quantity  of  water,  are  employed. 
The  acid  dissolves  the  excess  of  aniline  and  magenta,  which 
is  not  transformed  into  violet,  while  the  violet  remains  undis- 

*  Repert.  d.  Chem.  App.  Juillet,  1861,  p.  3.  273.    Dingler's  Pol.  Jour.,  vol. 
162,  p.  55. 
f  Monit.  Scient.,  1861,  p.  338. 


6o 


ANILINE  BLUE  AND  VIOLET. 


solved.  It  is  entirely  soluble  in  alcohol,  acetic  acid,  methyl 
alcohol,  and  boiling  water  containing  a  little  acetic  acid. 
All  these  solutions  may  be  used  at  once  for  dyeing. 

To  obtain  the  blue  colour,  the  violet  mass  is  boiled  several 
times  with  dilute  hydrochloric  acid  (10  parts  of  the  acid  to 
ioo  parts  of  water),  and  finally  washed  with  boiling  water. 
The  boiling  is  repeated  until  the  colour  is  pure  blue.  When 
cold  it  has  a  beautiful  copper-like  lustre.  To  use  this  colour 
for  dyeing,  it  is  dissolved  in  concentrated  acetic  acid,  alcohol, 
or  methyl  alcohol,  and  the  solution  thus  obtained  diluted 
with  water.  The  liquid  resulting  from  boiling  the  violet 
substance  with  water,  contains  hydrochlorate  of  aniline  and 
magenta ;  it  is  mixed  with  an  alkali,  which  precipitates  them 
after  a  little  time. 

Instead  of  producing  aniline  red,  then  purifying  it  and 
transforming  it  into  violet,  the  blue  colour  may  be  direftly 
obtained  by  treating  aniline  with  oxidising  agents,  in  which 
process  an  excess  of  aniline  must  be  employed.  This  method 
of  producing  aniline  violet  and  blue  has  been  already  men- 
tioned. 

According  to  the  specification  of  MM.  Girard  and  de 
Laire,  it  is  possible  to  get  every  shade  of  violet,  but  not  a 
blue.  Accordingly,  some  years  after  this  patent  was  sold  to 
Messrs.  Simpson,  Maule,  and  Nicholson,  of  London,  a  ma- 
nufacturer named  Levinstein  began  to  produce  aniline  blue, 
and  subsequently  a  law  suit  was  instituted  against  him  by 
Messrs.  Simpson,  Maule,  and  Nicholson. 

True  aniline  blue  is  always  produced  from  a  mixture  of 
aniline  red  and  aniline,  by  adding  an  organic  acid,  an  organic 
salt,  or  some  similar  substance  to  the  melted  mass.  M.  P. 
Bolley*  observed  that  by  adding  benzoic  acid  to  de  Laire's 
mixture,  a  good  result  was  obtained.  Acetic  acid  and  its 
salts  may  be  considered  the  chief  agent  for  the  transforma- 
tion of  aniline  red  into  blue  ;  and  other  organic  acids  also 
have  the  same  property.  Mr.  Price,  in  his  specification,  f 
dated  December  10,  1862,  says  that  three  parts  of  aniline 

*   DlNGLER,  VOl.  l68,  p.  6l. 

f  Lond.  Jour,  of  Arts,  Sept.,  1863,  p.  146.    Dingler,  vol.  170,  p.  219. 


ANILINE  BLUE  AND  VIOLET. 


6l 


are  to  be  employed  in  the  form  of  the  acetate,  valerianate, 
lactate,  benzoate,  tartrate,  or  oxalate.  This  is  to  be  mixed 
with  one  part  of  magenta,  and  heated  in  a  suitable  vessel  at 
a  temperature  of  from  1500  to  1900  C.  until  the  desired  shade 
is  obtained.  Mr.  W.  A.  Gilbee*  mixes  at  once  rosaniline, 
the  base  of  magenta,  with  aniline  and  acetic  acid,  and 
obtains  aniline  blue  by  heating  this  mixture.  To  purify  the 
substance  thus  obtained,  it  is  poured  into  exceedingly  dilute 
sulphuric  acid.  The  aniline  dissolves,  and  the  liquid  is 
filtered  to  obtain  the  blue  colouring  matter,  which  is  in- 
soluble in  water.  The  blue  is  then  boiled  with  water  until 
the  matter  comes  away  colourless.  When  cold,  the  blue 
forms  a  resinous  mass,  which  may  be  dissolved  by  triturating 
it  with  six  or  eight  times  its  weight  of  concentrated  sul- 
phuric acid.  The  solution  thus  obtained  is  poured  into  a 
large  quantity  of  water,  which  precipitates  the  colour.  By 
drying  the  precipitate,  the  colouring  matter  is  obtained  pure. 
If  the  solution  of  blue  in  concentrated  sulphuric  acid  is  heated 
for  twenty-five  or  thirty  minutes  before  pouring  it  into  water, 
the  precipitated  blue  is  soluble  in  boiling  water,  or  in  water 
containing  a  little  sulphuric  acid. 

Mr.  Schlumberger's  methodt  differs  from  the  above  only 
by  the  addition  of  a  quantity  of  caustic  soda  or  soda  crystals 
to  the  boiling  mass,  in  order  to  saturate  the  acetic  acid. 
Mr.  Passavant,  of  Bradford,  uses  acetate  of  soda  instead  of 
acetate  of  aniline,  or  the  mixture  of  acetic  acid  and  soda 
employed  by  the  former  chemists.  He  thus  gets  a  colour 
which  he  calls  a  night  blue,  or  bleu  de  nuit,  because  it  appears 
in  full  beauty  even  by  artificial  light.  According  to  the 
description  of  Mr.  Passavant's  method,!  4  parts  of  magenta 
are  mixed  with  8  parts  of  aniline  and  2  parts  of  acetate  of 
soda,  and  heated  for  2  hours  at  2000  C.  Finally,  the  tem- 
perature of  the  mixture  is  raised  to  250°  C.  If  the  desired 
shade  is  obtained,  the  semi-liquid  mass  is  taken  from  the  fire 
and  poured  into  4  parts  of  alcohol,  to  which  12  parts  of 

*  Lond.  Jour,  of  Arts,  March,  1863,  p/158.    Dingler,  vol.  168,  p.  141. 
f  Eng.  Patent  of  Jan.  14th,  1863. 
%  Pol.  Centralbl.,  1864,  p.  971. 


62 


ANILINE  BLUE  AND  VIOLET. 


hydrochloric  acid  have  been  added.  The  dark  brown  mass 
obtained  on  cooling  is  ground  and  then  boiled  for  a  quarter 
of  an  hour  in  water  containing  8  parts  of  sulphuric  acid.  The 
blue  residue  obtained  by  filtration  is  again  heated  twice  with 
8  parts  of  hydrochloric  acid  to  eliminate  the  trace  of  red 
shade  still  contained  in  the  blue,  after  which  the  mass  is 
boiled  several  times  with  water  to  remove  all  acid.  The  dry 
colouring  matter  is  ground  and  digested  with  io  parts  of 
alcohol  until  the  last  trace  of  red  is  removed.  The  method  of 
purification  above  described  is  too  precise  to  be  carried  out 
in  practice,  and  the  temperature  need  not  be  raised  as  de- 
scribed by  Mr.  Passavant. 

For  some  years  acetate  of  potash  has  been  substituted  for 
the  soda  salt,  because  the  greenish  shade  of  blue  now  so 
popular  is  obtained  more  easily  by  the  use  of  the  potash  salt. 
This  method  was  made  known  in  1864  by  Mr.  Levinstein, 
who  called  the  greenish  blue  bleu  de  nuit ;  this  differs  from 
the  bleu  de  nuit  of  Mr.  Passavant,  which  has  neither  a  red- 
dish nor  greenish  tinge,  but  is  a  pure  full  blue. 

Mr.  Levinstein's*  description  is  as  follows  : — Three  parts 
of  aniline  are  treated  with  one  part  of  magenta  at  a  tempera- 
ture of  1800  C.  until  the  red  is  transformed  into  violet,  which 
is  the  case  after  three  or  four  hours.  Then  half  a  part  of 
acetate  of  potash  is  added,  and  the  temperature  is  raised  to 
1900  C. ;  in  hours'  time  all  the  red  is  transformed  into  blue. 
The  mass  is  still  heated  until  a  small  quantity  taken  out  on 
a  white  plate  appears  of  a  greenish  blue  colour.  Then  the 
mass  is  treated  with  concentrated  hydrochloric  acid,  and  the 
bleu  de  nuit  is  thereby  obtained  as  a  solid  mass  of  a  red 
copper-like  metallic  lustre.  The  blue  which  remains  dis- 
solved in  the  acid  may  be  obtained  by  dilution  with  water. 
This  colour  is  generally  called  Bleu  de  Lyons. 

Instead  of  the  acetates  Mr.  Hollidayf  of  Huddersfield 
uses  benzoic  acid,  a  method  long  ago  introduced  into  aniline 
manufacture,  and  since  discontinued.  C.  G.  Williams!  mixes 

*  Pol.  Centralbl.,  vol.  65,  p.  350. 
f  Pol.  Centralbl.,  1864,  p.  971. 
J  Ibid.,  1864,  p.  971. 


ANILINE  BLUE  AND  VIOLET. 


63 


8  parts  of  oleate  of  aniline  with  one  part  of  rosaniline,  or  he 
uses  four  parts  of  oxalic  acid  with  four  parts  of  aniline,  which 
mixture  he  heats  to  from  1800  to  2000  C.  After  a  while  a  dark 
blue  mass,  soluble  in  spirit,  is  thereby  formed.  An  excess  of 
the  acid  or  of  aniline  is  afterwards  eliminated  by  treating  with 
dilute  sulphuric  acid  and  rectified  petroleum  or  photogen, 
whereby  a  copper-coloured  mass  remains,  which,  when  dis- 
solved in  spirit,  may  be  used  at  once  for  dyeing  purposes. 

We  proceed  now  to  describe  the  manufacture  of  aniline 
violet  and  blue  as  it  is  actually  carried  on  in  the  aniline 
manufactories,  with  the  proportions  found  to  be  most  advan- 
tageous in  practice. 

A  reddish  violet  can  be  easily  obtained  by  mixing  100 
parts  of  magenta  with  the  same  quantity  of  aniline  oil  and 
25  parts  of  acetate  of  soda.  The  mixture  thus  prepared  is 
heated  in  an  oil  bath  at  from  1700  to  1800  C.  until  the  desired 
shade  is  produced. 

For  making  violet  small  distilling  vessels  are  employed  of 
the  form  already  described  in  the  manufacture  of  magenta. 
In  this  case  the  ingredients  are  mixed  together  by  agitation. 
The  operation  is  watched  by  taking  out  a  little  of  the  liquid 
and  dissolving  it  in  spirit.  At  first  the  transformation  of  red 
into  blue  advances  slowly,  but  afterwards  more  quickly,  and 
at  last  so  rapidly  that  it  is  sometimes  difficult  not  to  over- 
pass the  desired  shade.  During  the  whole  process  a  vola- 
tilisation of  ammoniacal  gas  occurs,  formed,  as  will  be  shown 
hereafter,  by  the  adtion  of  aniline  on  magenta,  and  at  the 
same  time,  aniline  oil  distils  over.  This  is  collected  and 
mixed  in  suitable  proportion  with  another  oil,  as  already 
described  in  the  chapter  on  Aniline  (page  30) ;  it  may  then 
be  employed  in  a  second  operation. 

When  the  desired  shade  is  produced  the  vessel  will  contain 
a  more  or  less  liquid  mass,  consisting  of  undecomposed 
aniline  and  the  red  violet  colouring  matter  produced.  To 
eliminate  the  aniline  the  mass  is  ladled  out  as  quickly  as 
possible,  and  heated  with  very  dilute  hydrochloric  acid, 
which  dissolves  all  aniline  in  the  form  of  hydrochlorate,  the 
violet  remaining  at  the  top.  This  is  skimmed  off,  allowed 
to  cool,  and,  after  powdering,  may  be  sold.    Thus  prepared, 


64 


ANILINE  BLUE  AND  VIOLET. 


the  red  violet  colouring  matter  is  a  powder  much  resembling 
that  of  magenta,  but  not  so  greenish.  The  bluer  the  violet 
the  more  reddish  the  shade  of  the  lustre,  the  pure  blue  having 
a  decided  copper  red  lustre. 

To  get  the  bluer  shades  of  violet  the  same  proportions  may 
be  used,  but  the  operation  must  be  continued  longer.  To 
manufacture  a  blue  violet,  the  so-called  dahlia,  the  mass  is 
mixed  with  a  small  portion  of  a  substance  able  to  transform 
the  reddish  blue  into  a  greenish  one,  as  will  be  subsequently 
described.  The  process  can  thus  be  completed  much  more 
rapidly  than  in  the  ordinary  way.  After  taking  them  from 
the  retorts,  the  blue  violet  shades  are  to  be  heated  with  hydro- 
chloric acid,  just  as  the  reddish  shades. 

In  the  manufacture  of  aniline  blue  a  mixture  of  50  parts 
of  magenta,  150  parts  of  aniline,  and  50  parts  of  acetate  of 
soda  is  employed,  and  the  mass  is  heated  as  described  above. 
When  the  colour  of  the  mass  has  gone  beyond  the  bluest  of 
the  violet  shades,  it  becomes  a  reddish  blue.  This  is  a  very 
bright  colour,  formerly  much  admired.  The  substance  after- 
wards turns  to  a  pure  blue  colour,  which  has  no  red  or  green 
shade  in  it ;  this  is  the  so-called  full  blue.  It  was  formerly 
sold  under  the  name  of  Bleu  de  Fayolle,  and  can  never  have 
been  got  from  a  simple  mixture  of  aniline  and  magenta. 

After  the  blue  colour  is  obtained  the  mass  assumes  a 
greenish  blue  colour,  which  is  sold  under  the  names  of  Bleu 
de  Nuit,  Bleu  de  Lumiere,  Bleu  de  Mexique,  &c.  When  this 
shade  is  also  passed  the  blue  becomes  of  a  disagreeable 
greyish  shade,  and  is  now  good  for  nothing.  In  this  case  the 
colour  is,  as  aniline  manufacturers  say,  "  overgone." 

To  obtain  easily  and  quickly  the  blue  shades  some  addi- 
tions are  necessary,  which  I  shall  now  describe.  When  the 
above-mentioned  mixture  is  transformed  to  blue  violet  or  a 
reddish  blue  the  manufacturers  add  benzoic  acid,  benzoate 
of  potash  or  soda,  formiate  of  soda,  stearic  acid,  stearate  of 
soda,  common  soap,  or  some  similar  substance.  The  addi- 
tion is  made  gradually  in  small  quantities,  and  the  mass  is 
well  stirred  up,  and  the  effeCt  waited  for  for  some  minutes.  If 
the  effeCt  is  still  insufficient,  a  fresh  portion  is  added,  and  so 
on  till  some  minutes  after  the  last  addition  the  mass  assumes 


ANILINE  BLUE  AND  VIOLET. 


65 


the  desired  shade.  The  mass  must  then  be  taken  out  of 
the  vessel  as  quickly  as  possible,  for  this  removal  requires  a 
certain  time,  and  even  during  this  time  the  shade  of  the 
colour  may  be  altered  ;  it  is,  therefore,  best  to  transform  the 
mass  to  a  shade  a  little  redder  than  the  one  desired. 

Soap  has  been  largely  employed  as  an  addition,  especially 
of  late  years.  By  its  use  blue  violet  and  the  several  shades 
of  blue  are  obtained;  the  soap  used  is  a  common  tallow  soap, 
that  is  to  say,  impure  stearate  of  soda. 

To  get  a  blue  violet  f  part  of  soap  is  employed  where  the 
mixture  consists  of  1  part  of  aniline,  3  parts  of  magenta,  and 
f  part  of  acetate  of  soda.  For  blue,  J  part  of  soap  is  used 
for  every  3  parts  of  magenta.  The  liquid  mass  is  taken  out 
of  the  vessel,  as  already  described  in  the  preparation  of 
violet.  Sometimes,  if  a  blue  of  a  certain  shade  is  required, 
the  contents  of  the  vessel  are  immediately  poured  into  cold 
water  to  cool  them  quickly ;  but  this  adftion  is  so  uncertain 
that  it  is  employed  only  in  a  few  cases.  The  mass  is  treated 
in  the  usual  manner  with  dilute  hydrochloric  acid  to  elimi- 
nate an  excess  of  aniline ;  it  is  then  washed  in  pure  hot 
water  to  purify  it  from  all  acid.  If  stearate  of  soda  or  soap 
has  been  employed,  the  stearic  acid  set  free  by  heating  with 
hydrochloric  acid  must  be  removed.  This  is  effected  after 
drying  and  grinding,  by  heating  the  mass  with  benzol, 
which  dissolves  the  stearic  acid.  After  evaporating  off  the 
benzol  the  blue  colouring  matter  may  be  at  once  used. 

The  lustre  of  the  blue  mass  is  no  longer  green  but  quite 
red.  When  the  mass  is  ground  to  an  impalpable  powder  its 
colour  is  blue. 

In  this  operation  the  weight  of  the  blue  obtained  always 
exceeds  that  of  the  red  employed.  In  most  successful  opera- 
tions 150  parts  of  blue  may  be  got  from  100  parts  of  magenta. 

Both  the  blue  and  violet  are  insoluble  in  hot  and  cold 
water.  Only  a  little  undecomposed  red  can  be  extracted 
from  the  red  violet ;  but  both  violet  and  blue  are  soluble  in 
spirit,  methyl  alcohol,  aceton,  acetic  acid,  and  in  glycerin 
of  the  specific  gravity  of  rs.  From  all  these  solutions  the 
colours  are  precipitated  by  soluble  carbonates,  sulphates, 
acetates,  nitrates,  and  hydrochlorates ;  the  red  shades  of  violet 

F 


66 


ANILINE  BLUE  AND  VIOLET* 


are  rendered  bluer  by  sulphuric  acid  and  hydrochloric  acid. 
From  its  alcoholic  solution  blue  is  completely  precipitated 
by  tannic  acid.  Heated  on  platinum  foil  both  violet  and  blue 
volatilise  ;  they  are  also  dissolved  by  concentrated  hydro- 
chloric and  sulphuric  acid. 

By  the  adtion  of  monohydrated  sulphuric  acid,  S03,HO, 
the  blue  may  be  transformed  into  a  modification  soluble  in 
water.  Fuming  sulphuric  acid  is  usually  employed  for  this 
purpose.  After  the  blue  has  been  heated  for  some  time  with 
the  acid  it  is  poured  into  a  large  quantity  of  water,  whereby 
it  is  precipitated  as  a  blue  powder  soluble  in  hot  water  or 
dilute  acids. 

The  end  of  the  process  may  be  recognised  by  the  circum- 
stance that  the  blue  is  then  completely  soluble  in  a  solution 
of  crystals  of  soda.  The  whole  of  the  liquid  mass  is  then 
poured  with  constant  stirring  into  a  large  quantity  of  cold 
water,  whereby  the  blue  colour  is  precipitated  as  a  powder 
which  is  colle&ed  and  sold  under  the  name  of  Soluble  Blue. 
This  product  is  easily  soluble  in  hot  water,  or  water  con- 
taining a  few  drops  of  sulphuric  acid.  The  yield  of  soluble 
product  is  always  larger  than  the  common  blue  employed. 
A  soluble  violet  has  also  been  obtained  in  the  same  way,  but 
the  colour  assumes  a  disagreeable  greyish  shade  during  the 
process. 

It  has  been  found  that  the  decoftions  of  certain  roots  and 
barks  will  dissolve  aniline  colours.  Thus  M.  Gaultier  de 
Chaubry*  found  that  the  decoftion  of  the  quillaja  saponaria,  as 
well  as  the  Egyptian  soap  wort,  will  do  this.  The  same  effeft 
is  produced  by  a  decoftion  of  lime  soap,  and  other  similar 
substances. 

As  regards  the  composition  of  aniline  blue  and  violet  we 
have  already  mentioned  that  all  violets  may  be  regarded  as 
intermediate  products  between  red  and  blue.  MM.  Girard 
and  De  Lairet  observed  first  that  when  violet  or  blue  was 
formed  by  treating  the  red  colour  with  aniline  oil  ammonia 
gas  was  evolved.    Mr.  Nicholson  afterwards  showed  that  the 

*  Polyt.  Centralbl.,  1865,  p.  751.    Compt.  Rend.,  vol.  60,  p.  625.  Technol., 

VOl.  26,  p.  472.     DlNGLER,  VOl.  I76,  p.  23I. 

f  Dingler's  Polyt.  Journ.,  vol.  162,  p.  279. 


ANILINE  BLUE  AND  VIOLET. 


67 


blue  was  a  salt  of  a  colourless  base.  Dr.  A.  W.  Hofmann* 
then  investigated  the  hydrochlorate  of  the  blue  base,  which 
he  found  to  be  a  scarcely  crystallisable  substance  of  a  bluish 
brown  colour,  insoluble  in  cold  or  boiling  water  and  in  ether. 
Alcohol  dissolves  it  and  forms  a  bright  blue  colour.  When 
the  solution  is  evaporated  the  colour  remains  as  a  film  of  a 
lustre  half  gold  and  half  copper-coloured. 

According  to  several  analyses  of  this  substance  made  by 
Dr.  Hofmann  it  was  found  to  have  the  formula — 

C56H3IN3,  HC1, 

so  that  the  blue  may  be  considered  as  the  salt  of  a  base  dif- 
fering from  rosaniline,  C40H19N,  only  by  containing  three 
equivalents  of  the  radical  phenyl,  CI2H5,  instead  of  three 
equivalents  of  hydrogen,  and  the  blue  is  thus  the  hydro- 
chlorate  of  triphenylrosaniline, — 

M3(C;H5)}N3>  HCl. 

Its  formation,  during  which  ammonia  gas  is  developed,  may 
be  described  by  the  formula — 

C40HI9N3,  HCl  +  3N{Cl2^J  = 

Hydrochlorate  of  rosaniline,  Aniline, 
or  magenta. 

=  3NH3  +  c40f 


3icX)\N"  HC1' 


Ammonia.      Hydrochlorate  of  triphenyl- 
rosaniline, or  aniline  blue. 

The  pure  base  may  be  obtained  easily  by  treating  the 
hydrochlorate  with  alcoholic  ammonia,  whereupon  the  whole 
liquor  assumes  a  yellow  colour.  It  now  contains  pure  tri- 
phenylrosaniline and  hydrochlorate  of  ammonia.  By  boil- 
ing the  solution  thus  obtained,  ammonia  is  driven  off,  and 
the  pure  base  precipitated  of  a  white  or  greyish  colour.  To 
purify  the  base  dissolve  it  in  alcohol  saturated  with  ammonia, 
and  add  a  large  quantity  of  water.  Pure  triphenylrosaniline 
then  rises  to  the  surface  as  a  white  coagulum.  After  wash- 
ing and  drying  the  precipitate  assumes  a  bluish  tint ;  it 
melts  at  ioo°  without  loss  of  weight.    Up  to  the  present 

*  Compt.  Rend.,  part  59,  p.  25.  Annal.  de  Chem.  u.  Pharm.,  1863,  p,  437. 
Dingler,  vol.  170,  p.  58. 

F  2 


68 


ANILINE  BLUE  AND  VIOLET. 


time  it  has  been  found  impossible  to  crystallise  triphenyl- 
rosaniline,  although  it  is  soluble  in  both  ether  and  alcohol. 
On  analysis  the  pure  base  is  found  to  be  analogous  in  com- 
position to  the  hydrochlorate.    Its  formula  is — 

M3<c%}  N> +  2H0- 

As  it  is  impossible  to  form  a  true  violet  by  mixing  the  red 
and  the  blue  dye  together,  aniline  violet  must  be  an  inter- 
mediate compound  between  rosaniline  and  triphenylrosani- 
line;  either  mono-  or  di-phenylrosaniline.  We  have  explained 
the  composition  of  the  hydrochlorate  of  rosaniline  by  the 
formula  C40HI9N3,  HC1,  and  the  formulae  of  the  intermediate 
products  must  then  be  taken  as — 

C^{(C1aH5)}N3>  HCL 

and  c-{2(c:h5)}n-  hcl 

We  may  expedl  the  first  of  these  intermediate  products  to 
be  redder  than  the  second,  since  the  blue  hydrochlorate  has 
for  its  formula — 

c<°(3<?:Ih>S'hci- 

Monophenylrosaniline  then  produces  the  red,  and  diphenyl- 
rosaniline  the  blue  shade  of  violet.  It  is  very  probable  that 
the  redder  shades  of  violet  contain  a  little  of  the  pure  ros- 
aniline, in  the  same  way  that  the  blue  ones  certainly  contain 
a  small  quantity  of  the  most  substituted  product,  triphenyl- 
rosaniline  ;  and  it  is  found  that  by  treating  the  reddest 
shades  of  violet  with  dilute  hydrochloric  acid  a  little  of  the 
red  may  be  extrafted. 

Mr.  W.  H.  Perkin  has  separated  the  basis  of  his  violet 
(which  is  obtained  by  bichromate  of  potash  from  the  sul- 
phate of  aniline)  by  adding  potash  to  the  solution  of  this 
purple  colouring  matter.  The  solution  turns  bluish  and 
deposits  a  black  sparkling  precipitate.  After  being  dried 
this  substance  looks  like  specular  iron  ore,  and  is  the 
basis  of  Perkin's  violet,  called  by  this  chemist  mauveine. 
It  is  so  powerful  a  base  that  ammonia  is  expelled  by  it  from 
its  compounds.     Mr.  Perkin  has  given  to  mauveine  the 


ANILINE  BLUE  AND  VIOLET. 


69 


formula  C54H24N4,  the  composition  of  the  hydrochlorate 
being  indicated  by  the  formula  C54H24N4,  HC1.  The  hydro- 
chlorate*  of  this  new  base  is  the  best  known  of  the  compounds 
which  Mr.  Perkin  has  investigated.  It  is  obtained  by  adding 
hydrochloric  acid  to  a  solution  of  pure  mauveine  in  alcohol. 
By  boiling  the  solution  prismatic  crystals  may  be  obtained 
of  a  beautiful  greenish  metallic  lustre.  Chloride  of  platinum 
produces  with  the  hydrochlorate  of  mauveine  a  chloroplati- 
nate  of  the  formula  C54H24N4,  HC1  +  PtCl2,  a  substance  which 
has  a  metallic  lustre  as  beautiful  as  that  of  the  hydrochlorate. 

The  most  interesting  compound  of  this  base  is  its  car- 
bonate ;  no  other  base  derived  from  aniline  forms  a  salt  with 
this  acid.  To  prepare  it  carbonic  acid  gas  is  passed  through 
a  boiling  solution  of  mauveine  in  alcohol.  The  liquid  is 
allowed  to  cool,  when  it  precipitates  prisms  of  the  carbonate 
which  Mr.  Perkin  thinks  are  a  mixture  of  the  mono-  and  bi- 
carbonate of  the  purple  base — 

(C54H24N4  +  HO)  C02, 
and  (C54H24N4  +  HO),  C02  +  HO,  C02. 

Upon  heating,  the  colour  of  mauveine  and  its  salts  is 
changed  to  blue. 

Reducing  agents  decolourise  triphenylrosaniline  in  the 
same  manner  as  rosaniline.  The  aniline  blue  takes  up  two 
equivalents  of  hydrogen,  and  a  substituted  leukaniline — 
triphenylleukaniline — is  produced.  The  composition  of  this 
substance  is  expressed  by — 

c  f  ^i8  In 

M3(cI2H5)r3> 

the  formula  of  the  blue  being — 

This  new  colourless  base  can  be  produced  by  treating  a 
solution  of  triphenylrosaniline,  the  common  blue,  with  hydro- 
chloric acid  and  zinc.  The  solution  becomes  quickly  de- 
colourised, when  a  large  quantity  of  water  is  to  be  added, 
whereupon  a  difficultly  crystallisable  white  precipitate  is 
obtained.  This  precipitate  must  be  separated  by  washing 
from  the  chloride  of  zinc ;  it  may  then  be  obtained  quite 

*  Kopp,  Bulletin  de  la  Societe  Industrie  de  Mulhouse,  Avril,  1865,  p.  167. 


70 


ANILINE  BLUE  AND  VIOLET- 


pure  by  dissolving  in  ether  and  evaporating.  Oxidising 
agents  reproduce  triphenylrosaniline  from  triphenylleukani- 
line.  A  little  chloride  of  platinum  added  to  a  solution  of 
the  latter  immediately  turns  it  blue. 

We  have  already  shown  that  it  is  possible  to  substitute 
an  organic  radical — phenyl,  (CI2H5) — for  the  hydrogen  of 
rosaniline  ;  it  is  not  then  surprising  to  find  other  radicals 
replacing  this  hydrogen.  In  fact,  A.  W.  Hofmann*  has  suc- 
ceeded in  substituting  for  this  hydrogen  the  radicals  of  the 
different  alcohols — methyl,  ethyl,  and  amyl ;  the  substitution 
being  effected  by  treating  rosaniline  in  a  sealed  tube  with  the 
iodide  of  any  of  the  above  radicals.  The  product  is  an 
excessively  blue  coloured  mass,  giving  an  alcoholic  solution 
of  a  splendid  bluish  violet  colour.  The  dyeing  powers  of 
this  substance  are  not  inferior  to  those  of  rosaniline  itself. 
This  produdt  is  the  iodide  of  the  new  substitution  base.  To 
obtain  the  pure  substance,  take  the  mass  out  of  the  sealed 
tube,  decompose  it  with  caustic  soda,  and  heat  the  new  sub- 
stitution base,  as  it  is  still  mixed  with  a  little  rosaniline, 
once  more  with  the  alcoholic  iodide.  By  twice  repeating 
this  operation  a  soft  resinous  substance  results,  which  is 
transformed  by  heating  with  water  into  a  hard  crystalline 
mass  of  a  bright  metallic  lustre.  The  pure  substance 
obtained  by  crystallising  from  the  solution  in  alcohol  yields 
on  analysis  the  formula — ■ 


That  is  to  say,  the  new  substance  contains  as  a  basis  ros- 
aniline, in  which  three  equivalents  of  hydrogen  are  replaced 
by  ethyl  (C4H5)  the  radical  of  alcohol.  Even  in  the  hydri- 
odic  acid  united  with  this  new  base  the  hydrogen  is  replaced 
by  ethyl,  so  the  new  substance  must  be  called  ethyliodate  of 
triethylrosaniline. 

The  salts  of  triethylrosaniline  are  known  under  the  name 
of  "  Hofmann's  Violet,"  and  according  to  the  specification  of 
that  chemist's  patent  of  May  22nd,  1863,  are  made  as  fol- 
lows : — 


*  Dingler's  Polyt.  Journal,  vol.  170,  p.  62.  Comptes  Rendus,  part  57,  p.  25. 
Journ.  f.  Chem.  und  Pharm.,  1863,  p.  473. 


ANILINE  BLUE  AND  VIOLET. 


7* 


One  part  of  magenta,  two  parts  of  iodide  of  ethyl,  and 
about  two  parts  of  strong  methyl  or  ethyl  alcohol  are  heated 
in  a  convenient  close  apparatus  at  a  temperature  of  2120  F. 
The  vessel  used  must  be  made  of  sufficient  strength  to  resist 
the  pressure  of  the  vapour.  The  heating  is  continued  from 
three  to  four  hours,  or  until  the  whole  mass  assumes  a  violet 
colour.  The  vessel  is  then  allowed  to  cool.  When  cool  it 
is  opened,  and  the  tarry  substance  dissolved  in  methylic  or 
ethylic  alcohol.  This  solution  may  be  employed  immediately 
for  dyeing. 

To  save  the  iodine,  which  is  expensive,  the  above  sub- 
stance when  taken  out  of  the  vessel  may  be  heated  with  an 
alkali.  By  this  process  the  pure  base  of  this  colouring 
matter  is  got  as  an  insoluble  powder,  and  the  iodine  is  dis- 
solved by  the  alkali.  The  precipitated  base  must  be  washed 
and  dissolved  in  alcohol  containing  hydrochloric  acid.  The 
colouring  matter  thus  produced  dyes  wool  and  silk  in  beauti- 
ful red  and  blue  violet  shades. 

The  iodide  of  methyl,  amyl,  propyl,  or  capryl,  may  be 
used  instead  of  the  iodide  of  ethyl  in  the  above  process,  and 
instead  of  iodine,  bromine  may  be  used.  The  new  violet 
has  a  richer  colour,  and  its  shades  are  brighter  than  those  of 
the  common  aniline  violet.  It  was  at  first  manufactured  by 
the  firm  of  Simpson,  Maule,  and  Nicholson,  to  whom  the 
patentee  sold  his  privilege.  Soon  after,  a  German  manu- 
facturing chemist,  Mr.  Rudolph  Knosp,  of  Stuttgard,  began 
to  make  this  violet,  and  it  is  now  made  by  every  continental 
manufacturing  chemist.  When  dry  it  has  a  splendid  metallic 
lustre.    It  is  sold  also  under  the  name  of  primula. 

In  the  manufacture  of  Hofmann's  violet  on  the  large 
scale,  the  proportion  of  iodide  of  ethyl  is  considerably 
diminished  in  order  to  save  the  expense  of  the  iodine. 
According  to  my  own  researches,  twelve  parts  of  iodide  of 
ethyl  are  sufficient  to  transform  sixteen  parts  of  magenta 
into  Hofmann's  violet. 

It  is  remarkable  that  German  chemists  did  not  at  first 
succeed  in  producing  the  blue  shades  of  violet,  which  are  so 
easily  obtained  in  England,  and  the  bluish  shades  could  only 
be  produced  by  using  iodide  of  methyl  instead  of  iodide  of 


72 


ANILINE  BLUE  AND  VIOLET* 


ethyl.  This  interesting  point  is  easily  explained,  for  the 
methyl  substitute  formed  by  using  iodide  of  methyl  is  of  an 
intensely  blue  colour.  It  was  not  necessary  for  English 
chemists  to  make  a  direCt  use  of  this  methyl  compound, 
since  at  the  exorbitant  price  of  alcohol  the  much  cheaper 
methyl  alcohol  was  always  used  in  England  to  dissolve  the 
magenta,  and  to  render  it  capable  of  transformation.  Methyl 
alcohol  yields  with  iodide  of  ethyl,  at  a  high  pressure,  ethyl 
alcohol  and  iodide  of  methyl.    The  reaction  is — 

C2H30,  HO    +    C4H5I    =  C4H50,  HO  +  C2H3I. 

Methyl  alcohol.  Iodide  Ethyl  alcohol.  Iodide  of 

of  ethyl.  methyl. 

Indeed,  after  substituting  for  ethyl  alcohol,  methyl  alcohol, 
the  German  manufacturers  also  obtained  bluish  violet  shades. 
According  to  my  specification,  for  16  parts  of  magenta  and 
12  parts  of  iodide  of  ethyl,  there  must  be  employed  16  parts 
of  methyl  alcohol  and  2  to  4  parts  of  acetate  of  potash, 
which  it  is  best  to  dissolve  beforehand  in  the  alcohol. 

The  vessels  employed  for  manufacturing  Hofmann's  violet 
consist  of  iron  cylinders  coated  inside  with  lead  or  enamel, 
and  capable  of  being  closed  tightly  with  a  lid  provided  with 
screws.  After  filling  the  apparatus  with  the  above  mixture 
the  cover  is  to  be  fastened  down,  and  rendered  perfectly 
tight  by  means  of  a  lead  washer.  The  whole  apparatus  is 
then  put  into  a  vat  filled  with  boiling  water,  which  is  heated 
by  a  current  of  steam.  Usually  the  temperature  of  ioo°  C. 
is  exceeded,  the  apparatus  being  heated  to  no°  C,  for  which 
purpose  common  salt  or  chloride  of  calcium  is  added  to  the 
water  to  raise  its  boiling  point.  After  heating  from  four  to 
six  hours,  the  red  colour  is  transformed  into  violet,  the  shade 
of  which  depends  on  the  length  of  time  the  heat  has  been 
continued.  If  the  same  apparatus  is  always  used  and  it  is 
filled  with  the  same  quantity  of  mixture,  the  manufacturer 
learns  after  a  few  trials  to  produce  the  required  shade  by 
regulating  the  time. 

The  heating  being  finished,  the  apparatus  is  taken  out  of 
the  boiling  water  with  a  pair  of  tongs,  and  allowed  to  cool, 


ANILINE  BLUE  AND  RED. 


73 


after  which  it  is  opened.  The  opening  must  be  cautiously 
effected,  as  a  certain  quantity  of  permanent  gas  is  always 
produced  by  the  reaction,  probably  pure  ethyl  and  methyl 
gas,  which  being  absorbed  by  the  liquid  at  this  high  tempera- 
ture, now  suddenly  volatilises  when  the  pressure  is  diminished 
and  may  easily  cause  an  overflowing  and  loss  of  liquid. 

The  liquid  is  then  transferred  to  a  distilling  apparatus 
heated  by  steam,  where  the  excess  both  of  iodide  and  of 
alcohol  is  separated  from  the  solid  violet  substance.  The 
residue,  after  distillation,  forms  a  mass  of  a  beautiful 
metallic  lustre,  and  is  a  compound  of  the  new  ethylated  and 
methylated  base  with  hydriodic  acid.  To  separate  it  from 
the  latter  it  is  thrown  into  a  boiling  solution  of  soda,  which 
forms  iodide  of  sodium,  the  pure  base  floating  as  a  tarry 
mass  of  metallic  lustre  on  the  top  of  the  liquid.  It  is  to  be 
collected  with  a  ladle,  allowed  to  cool,  and  pulverised ;  it  is 
then  ready  for  sale. 

By  employing  iodide  of  methyl  for  the  ethyl  compound,  or 
by  adding  methyl  alcohol  to  the  latter,  a  methylated  base  is 
obtained,  the  acid  compounds  of  which  are  soluble  in  water. 
A  violet  thus  prepared  and  afterwards  treated  with  hydro- 
chloric or  sulphuric  acid,  yields  soluble  Hofmann's  violet. 

Iodide  of  ethyl  or  methyl  adapted  for  the  production  of 
violet  may  be  best  obtained  by  a  method  invented  by  myself.* 
According  to  this  method  a  Woulff 's  bottle  of  earthenware  is 
put  into  a  vat  filled  with  straw,  into  which  a  current  of  steam 
can  be  introduced  through  a  convenient  pipe.  One  of  the 
openings  of  the  bottle  is  closed  with  a  tight  cork,  the  other 
supports  a  large  upright  leaden  tube,  to  which  it  is  tightly 
attached.  This  tube  is  closed  below  by  a  sieve-like  lead 
plate  on  to  which  iodine  is  introduced  from  above  through 
the  tube.  The  upper  end  of  the  tube  is  closed  in  the  follow- 
ing manner.  Around  the  mouth  runs  a  gutter  lip  which  is 
filled  with  melted  paraffin  ;  when  the  mouth  of  the  tube  is 
covered  with  the  leaden  lid  which  fits  into  the  gutter  the 
tube  is  perfectly  closed.  Below  the  gutter  another  smaller 
leaden  tube  is  inserted  in  the  side  of  the  first,  and  leads  up- 

*  Dingler's  polyt.  Journ.,  vol.  181,  p.  28a. 


74 


ANILINE  BLUE  AND  RED* 


wards  to  a  coiled  worm  tube  for  cooling.  Phosphorus  in 
small  pieces  is  put  into  the  WoulfFs  bottle,  and  a  sufficient 
quantity  of  ethylic  or  methylic  alcohol  is  then  added,  after 
which  the  opening  of  the  bottle  is  closed  by  the  stopper,  and 
st££m  is  introduced  through  the  pipe  into  the  vat  so  as  to 
heat  the  whole  apparatus.  The  alcohol  in  the  bottle  begins  to 
boil  and  volatilises  through  the  vertical  leaden  tube.  When 
it  reaches  the  worm  tube  above  it  is  condensed,  and  runs  down 
again  in  a  liquid  state  upon  the  iodine  which  was  placed,  as 
above  described,  on  the  leaden  sieve-like  plate.  Here  the 
iodine  is  dissolved,  and  passes  in  the  form  of  an  alcoholic 
solution  through  the  plate  into  the  bottle,  where  at  the  high 
temperature  the  iodine,  alcohol,  and  phosphorus  are  trans- 
formed into  iodide  of  methyl  (or  ethyl,  according  to  the  nature 
of  the  alcohol  used,)  and  phosphoric  acid. 

When  all  the  iodine  in  the  tube  is  consumed,  the  boiling 
is  interrupted  for  some  moments,  and  a  fresh  supply  added 
by  taking  off  the  lid  of  the  leaden  tube.  Large  quantities  of 
alcohol  and  iodine  can  thus  be  transformed  into  iodide  with- 
out any  of  the  danger  which  is  found  to  attend  the  use  of 
all  other  apparatus.  When  all  the  alcohol  is  converted  the 
liquid  is  taken  from  the  bottle  and  washed.  Iodide  of  ethyl 
being  almost  insoluble  in  water  is  thus  obtained  pure.  The 
residue  of  phosphorus  in  the  bottle  is  heated  with  fresh  quan- 
tities of  alcohol  and  iodine  until  it  is  quite  consumed. 

After  these  remarks  upon  the  acetyl  substitutes  of  rosani- 
line  it  now  remains  to  speak  of  other  substitutes*  of  aniline 
investigated  by  A.  W.  Hofmann. 

When  rosaniline  is  heated  in  a  retort  a  liquid  distils  which 
has  been  found  to  be  aniline.  If  ethylrosaniline  is  distilled 
the  liquid  obtained  is  ethylaniline,  or  since  aniline  is  more 
properly  called  phenylamine — 

Cih:)n 

we  may  call  it  ethylphenylamine — 

C4H5  f-N. 
H  J 

« 

*  Jour.  Prac.  Chemie,  vol.  23,  p.  208.    Pol.  Centralbl.,  1865,  p.  325. 


ANILINE  BLUE  AND  VIOLET. 


75 


M.  Charles  Girard,  of  Lyons,  has  submitted  aniline  blue — 
phenylrosaniline — to  distillation,  and  has  thereby  obtained  at 
3000  C.  a  liquid  which,  allowed  to  cool,  solidified  to  a  solid 
crystalline  mass,  the  formula  of  which  was  found  bj^JJo^ 
mann  to  be —  .   ;  <  £>l  N 


CI2H5)  v<^'  j 


H)  /C,,-^ 


ft* 


This  new  substance  is  therefore  a  phenylamine  (an^Hn^)  yti 
which  another  atom  of  hydrogen  is  replaced  by  pfrenyT(Ci2tl5). 
Accordingly  we  may  call  it  diphenylamine.  Both  dipheny- 
lamine and  its  salts  yield  with  oxidising  agents  blue  sub- 
stances which  can  be  used  as  dyes.  A  solution  of  dipheny- 
lamine is  instantly  coloured  blue  by  nitric  acid.  MM.  Girard 
and  de  Laire,  of  Lyons,  have  produced  diphenylamine  in  a 
cheaper  manner  for  manufacturing  purposes.  They  heat  in 
a  closed  vessel  hydrochlorate  of  aniline  with  aniline,  by 
which  diphenylamine  is  formed,  and  ammonia  is  given  off. 
The  reaction  may  be  expressed  by  the  formula — 


Ci2^51n,  HC1  +  Ci2^4n  =c!"hJ|n,  HC1  +  NH3 


H 


Aniline.  Aniline.  Diphenylamine.  Ammonia. 

The  diphenylamine  thus  obtained  is  transformed  into  the 
blue  colouring  matter  by  heating  in  a  closed  apparatus 
with  bichloride  of  carbon.  M.  Briunneyr,  of  Echternach 
(Luxemburg),  has,  however,  discovered  a  new  and  much 
cheaper  method  of  transforming  diphenylamine  into  the  blue 
dye. 

As  aniline  yields  with  rosaniline  the  aniline  blue  triphenyl- 
rosaniline,  so  toluidine,  the  homologue  of  aniline,  gives  a 
blue  the  compounds  of  which  are  similar  to  those  of  the 
common  blue,  the  only  difference  between  the  two  substances 
being  that  the  substitution  is  effected  in  the  case  of  the  aniline 
blue  by  phenyl  (CI2H5),  while  in  the  toluidine  dye  the  radical 
of  this  latter,  tolyl  (CI4H7),  takes  the  place  of  the  substituted 
hydrogen.  Thus,  the  process  of  preparation  being  the  same, 
instead  of  the  phenyl  substitute,  tritolylrosaniline, — 

3(CI4H7)J 


N3 


76 


ANILINE  BLUE  AND  VIOLET. 


is  obtained.  Toluidine  blue  is  more  soluble  than  the  common 
blue,  this  being  almost  the  only  difference  between  these  two 
interesting  colouring  matters. 

In  the  same  manner  in  which  A.  W.  Hofmann  has  ob- 
tained a  violet  colour  from  rosaniline  by  means  of  iodide  of 
ethyl,  Mr.  W.  H.  Perkin*  has  produced  a  similar  colour  by 
treating  magenta  with  the  so-called  brominated  oil  of  turpen- 
tine ;  his  patent  is  dated  Sept.  6,  1864. 

To  obtain  this  violet  the  inventor  adds  brominated  oil  of 
turpentine,  manufactured  by  the  process  about  to  be  men- 
tioned, to  magenta,  and  heats  this  mixture  with  a  suitable 
quantity  of  alcohol  or  methyl  spirit  in  a  closed  vessel  at 
1400 — 1500  C,  which  temperature  is  continued  for  eight  hours. 
In  this  manner,  according  to  Mr.  Perkin's  specification,  a 
blue  violet  shade  is  obtained  by  filling  an  enamelled  iron 
vessel  with  a  mixture  of  one  part  of  magenta  and  six  parts 
of  brominated  turpentine.  When  closed  the  vessel  is  heated 
to  1400 — 1500  C,  which  temperature  is  kept  up  for  eight 
hours.  The  vessel  is  allowed  to  cool  and  is  then  emptied  ; 
its  contents  are  dissolved  in  methyl  alcohol,  and  may  be  em- 
ployed at  once  for  dyeing  and  printing.  To  get  a  redder 
shade  of  violet  three  parts  of  magenta  and  two  parts  of  bromi- 
nated turpentine  are  heated  together  in  the  above  manner. 

Brominated  oil  of  turpentine  is  obtained  by  filling  a  bottle 
of  a  capacity  of  about  z\  litres  half  full  of  water.  Bromine 
is  then  added  in  sufficient  quantity  to  cover  the  bottom  of 
the  bottle  about  inches  high.  A  layer  of  turpentine  oil 
is  poured  on  the  water.  On  agitation  the  bromine  combines 
with  the  oil,  which  then  sinks  to  the  bottom.  A  fresh  layer 
of  oil  may  be  added,  and  the  process  repeated  as  before ;  thus 
as  much  brominated  turpentine  oil  can  be  obtained  as  is  re- 
quired. A  want  of  bromine  can  be  easily  recognised  by  the 
disappearance  of  the  characteristic  bromine  colour. 

*  London  Journ.  of  Arts,  August,  1865,  p.  94.  Dingler's  pol.  Jour.,  vol. 
i77>P-405. 


CHAPTER  VI. 


ANILINE  GREEN. 

It  has  been  known  for  several  years  that  salts  of  aniline, 
especially  the  nitrate  of  this  base,  yield,  on  being  exposed  to 
the  influence  of  the  atmosphere,  blue  and  green  efflorescences, 
such  as  are  found  on  the  outside  of  the  vessels  containing 
these  salts.  But  a  green  dye  has  only  lately  been  obtained 
by  oxidising  aniline  salts. 

The  violet  obtained  by  MM.  Depouilly  and  Lauth  is 
quickly  transformed  into  a  green  mass  by  a  solution  of  chlo- 
rate of  potash.  A  green  precipitate  is  thus  obtained,  which 
at  8o°  C.  assumes  a  blue  colour.  The  liquid  separated, 
according  to  Mr.  Willm,  dyes  wool,  which  after  exposure  to 
the  atmosphere  assumes  a  green  colour. 

In  i860  an  English  patent  was  granted  to  Messrs.  Lowe, 
Calvert,  and  Clift*  for  producing  on  the  fibre  itself  an  insoluble 
green  colour,  emeraldine,  which  could  be  transformed  by 
alkalis  into  blue.  The  inventors  impregnated  the  fabric  to 
be  dyed  with  an  oxidising  substance,  viz.,  a  solution  of 
4  ounces  of  chlorate  of  potash  in  10  pounds  of  water,  dried  it 
and  treated  it  with  a  solution  of  an  aniline  salt  containing 
1  per  cent  of  aniline.  They  usually  employ  for  this  purpose 
the  tartrate  or  hydrochlorate  of  aniline.  The  fabric  is  then 
left  to  hang  for  12  hours  in  a  warm  damp  place.  This  method 

*  Repert.  of  Pat.  Inventions,  1861,  p.  199. 


78 


ANILINE  GREEN. 


is  therefore  quite  similar  to  that  of  Mr.  Willm.  To  save  one 
operation  the  fabric  may  be  immediately  impregnated  with 
a  mixture  of  3  pounds  of  a  solution  of  the  bitartrate  of  ani- 
line (which  contains  1  pound  of  aniline),  60  pounds  of  starch, 
and  1  pound  of  chlorate  of  potash.  This  last  is  dissolved 
in  the  paste  while  still  hot,  but  the  solution  of  aniline  is 
only  added  after  it  has  been  allowed  to  cool. 

The  green  colour  produced  by  these  methods  can  be  trans- 
formed into  a  blue  by  washing  the  fabric  with  soda  or  soap. 
For  10  pounds  of  water  1  ounce  of  soda  or  4  ounces  of  soap 
is  used.  A  solution  of  1  ounce  of  bichromate  of  potash  in 
10  pounds  of  water  produces  the  same  effeft. 

On  the  same  principle  is  founded  the  method  of  producing 
green.  According  to  the  Muster  Zeitung,*  10  parts  of 
aniline  are  mixed  with  15  parts  of  nitric  acid  diluted  before- 
hand with  6  or  8  times  its  weight  of  water.  The  mixture  is 
then  thickened  by  gum  Arabic  or  British  gum.  To  the  paste 
thus  obtained  are  added  10  parts  of  sugar,  and  from  4  to  8  parts 
of  pulverised  chlorate  of  potash  or  soda.  Cotton  printed  with 
such  a  paste  assumes  a  beautiful  green  colour  on  remaining 
24  to  36  hours  in  the  atmosphere.  Washed  with  water  con- 
taining some  acid  the  samples  keep  their  green  colour; 
treated  with  an  alkaline  solution  they  become  blue.  This 
blue  can  be  re-transformed  into  green  by  an  acid.  The  green 
and  blue  colours  therefore  are  probably  different  compounds 
of  the  same  substance,  as  we  have  seen  so  often  to  be  the 
case. 

All  the  processes  above  described  gave  an  unsatisfactory 
result,  and  therefore  a  mixture  of  aniline  blue  with  picric 
acid  was  employed  instead  of  a  real  aniline  green.  But  this 
had  the  great  defedt  of  not  looking  well  in  artificial  light, 
having  at  night  a  greyish  shade. 

The  firm  of  J.  J.  Miiller  and  Co.,  of  Basle  (now  Geigy),  suc- 
ceeded in  1861,  after  many  fruitless  attempts,  in  discovering 
an  aniline  green  with  which  dyeing  is  not  more  difficult  than 
with  any  other  aniline  colour,  and  whose  shades  are  as  bright 
as  possible  both  in  artificial  and  in  sun  light.     Not  long 

*  1861,  No.  6. 


ANILINE  GREEN. 


79 


afterwards,  also,  the  firm  Meister  Lucius  and  Co.,  in  Hochst, 
near  Frankfort-on-Maine,  began  to  prepare  a  green  colour. 
Several  Rhenish  firms  then  manufactured  it  also.  In  Fe- 
bruary, 1864,  a  patent  was  granted  to  the  house  of  L.  J.  Levin- 
stein, of  Berlin,  for  a  method  of  preparing  a  green  colouring 
matter  from  aniline. 

We  have  already  shown  that  by  treating  a  solution  of 
magenta  in  dilute  sulphuric  acid  with  aldehyd,  a  violet  or 
blue  colour  may  be  obtained.  By  continuing  this  treatment 
the  colour  is  changed  into  green  ;  but  this  green  is  still  not 
durable,  and  to  give  it  this  property  another  ingredient  must 
be  added.  Four  parts  of  well  crystallised  magenta  are  dis- 
solved in  a  mixture  of  6  parts  of  common  sulphuric  acid  and 
2  parts  of  water.  This  solution  is  heated  at  ioo°  C.  with 
16  parts  of  aldehyd  until  the  liquid  so  prepared  colours  a 
weak  solution  of  sulphuric  acid  blue ;  at  the  same  time  the 
liquid  assumes  a  greenish  hue.  If  the  aldehyd  employed  is 
impure  the  colour  of  the  sulphuric  acid  will  be  not  blue,  but 
reddish  blue  or  a  dirty  violet.  Hence  the  beauty  of  aniline 
green  depends  in  great  degree  upon  the  purity  of  the  aldehyd 
employed.  I  will  here  describe  the  manufacture  of  this 
product. 

The  name  aldehyd  was  introduced  by  Liebig,  the  disco- 
verer, and  is  derived  from  the  words  alcohol  dehydrogenatus. 
This  chemist  produced  aldehyd  by  depriving  alcohol  of  a  part 
of  its  hydrogen  : — 

C4H50,  HO  —  2  H  =  C4H30,  HO. 

v.  f  — »  ,   ^  r  

Alcohol.        Hydrogen.  Aldehyd. 

It  is  one  of  the  compounds  of  the  organic  radical  acetyl 
(C4H3)  with  oxygen,  and  contains  only  one  atom  of  oxygen, 
the  higher  oxidised  compound  of  this  radical  being  acetic 
acid.  Hence  aldehyd  is  easily  transformed  into  acetic  acid 
by  the  addition  of  oxygen  : — 

C4H30,  HO  +  20  =  C4H303,  HO. 

Aldehyd.         Oxygen.         Acetic  acid. 

Aldehyd  takes  oxygen  from  every  substance  able  to  give 
this  element,  and  is  therefore  a  very  strong  reducing  agent. 


8o 


ANILINE  GREEN. 


In  order  to  obtain  a  pure  aldehyd  for  the  above  purpose 
this  substance  is  produced  as  follows : — A  large  retort, 
provided  with  a  second  opening,  is  filled  to  the  extent  of 
one-third  of  its  capacity  with  a  mixture  of  30  parts  of  bichro- 
mate of  potash  and  32  parts  of  absolute  alcohol.  The  retort 
is  then  put  into  a  sand-bath,  and  surrounded  with  dry  sand 
as  high  as  it  is  filled  inside  with  the  mixture.  The  neck  of 
the  retort  is  fitted  to  a  condensing  apparatus,  a  long  metallic 
worm-pipe  being  best.  Having  put  a  receiver  under  the 
opening  of  the  cooling  pipe,  and  a  Welter's  safety  funnel  in 
the  tubulus  of  the  retort,  we  may  cotnmence  the  process. 

A  hot  mixture  of  35  parts  of  sulphuric  acid  and  30  parts 
of  water  are  added  in  small  portions  to  the  alcohol  in  the 
retort.  The  liquid  within  soon  begins  to  boil,  and  a  green 
scum  appears  on  the  top  ;  at  the  same  time  a  strong  current 
of  aldehyd  vapour  passes  over.  The  cooling  must  now  be 
very  perfect,  otherwise  the  vapours  easily  cause  an  explosion. 
As  soon  as  the  reaction  of  the  liquid  begins  the  addition  of 
sulphuric  acid  must  cease ;  when  the  first  and  strongest 
reaction  is  over  the  rest  of  the  sulphuric  acid  may  be  poured 
in.  During  the  whole  operation  it  is  unnecessary  to  heat  ; 
heating  is  even  very  dangerous,  because  by  the  rapid  develop- 
ment of  aldehyd  vapour  the  whole  apparatus  may  be  easily 
destroyed,  while  the  distillate  is  weakened  by  the  steam 
becoming  mixed  with  the  aldehyd  vapour.  Thus  produced 
the  aldehyd  can  be  at  once  employed  for  manufacturing  the 
green  dye.  It  has  an  extremely  choking  odour.  As  it  boils 
at  a  low  temperature  it  must  be  preserved  very  cautiously. 

The  solution  of  rosaniline,  treated  as  before  described 
with  aldehyd,  is  added,  with  continued  agitation,  to  a  boiling 
solution  of  subsulphide  of  soda,  by  which  two  different  colours 
are  formed.  The  liquid  assumes  a  beautiful  green  colour, 
and  a  greyish  blue  substance  is  suspended  in  it.  The  latter 
is  obtained  in  a  much  larger  quantity  than  the  soluble  green, 
and  can  only  with  great  difficulty  be  separated  from  its 
solution. 

This  greyish  blue  colouring  matter  can  be  obtained  pure 
by  filtering  the  solution,  and  forms  when  dry  a  mass  of  a 
copper-like  metallic  reflection.    It  is  sold  usually  under  the 


ANILINE  GREEN. 


8l 


name  of  Argentine.  Argentine  is  obtained  in  a  much  larger 
quantity  than  the  green  colour,  and  the  latter  being  very 
costly,  cannot  well  be  introduced  into  dye  works. 

The  green  colouring  matter  can  be  transformed  into  its 
bluer  shades  by  saturating  its  solution  with  alkalies,  and 
even  into  blue  if  supersaturated  with  carbonate  of  soda,  being 
at  the  same  time  precipitated.  The  colouring  matter  thus 
produced  has  been  sold  by  some  manufacturers,  but  it  can 
only  be  dissolved  by  heating  and  adding  much  acid,  and  its 
shades  are  not  so  bright  as  those  of  a  green  precipitated  in 
another  manner. 

To  obtain  a  green  with  a  splendid  lustre  add  to  its  solu- 
tion a  sufficient  quantity  of  acetate  of  soda,  whereby  it  is 
precipitated  as  a  beautiful  light  green  mass  which  may  be 
separated  by  filtering  through  cotton.  By  this  process  the 
colouring  matter  is  obtained  in  a  cake,  and  may  be  converted 
into  an  anhydrous  powder  by  drying  at  500  C.  The  price  of 
this  colour  was  already  high,  owing  to  the  expensive  opera- 
tions above  described,  and  is  heightened  still  more  by  this 
mode  of  treatment :  hence  this  aniline  green  can  only  be  em- 
ployed for  dyeing  silk,  although  it  is  exceedingly  beautiful 
and  bright,  and  appears  still  more  brilliant  by  artificial  light. 
It  is  known  under  the  names  of  Aniline  Green,  Emeraldine, 
Viridine,  and  Aldehyd  Green. 

According  to  the  specifications  of  M.  E. Lucius'*  patent  of 
the  year  1864,  the  production  of  this  green  can  be  effected 
also  by  means  of  hydrosulphuric  acid.  This  chemist  dis- 
solves one  part  of  sulphate  of  rosaniline  in  a  mixture  of  two 
parts  of  sulphuric  acid  and  two  to  four  parts  of  water,  to 
which  he  adds  four  parts  of  aldehyd,  and  heats  the  whole 
mixture  to  500  C.  The  test  whether  the  solution  is  suffi- 
ciently heated  is  the  same  as  before.  The  mixture  is  then 
added  to  from  300  to  500  parts  of  a  saturated  solution  of 
hydrosulphuric  acid  in  water,  and  the  whole  is  heated  to  900 
or  ioo°  C,  at  which  temperature  10  or  12  parts  of  a  saturated 
solution  of  sulphurous  acid  are  added.    After  being  allowed 

*  Polyt.  Centralbl.,  1864,  p.  1596  and  1659.  Chem.  Centralbl.,  1864,  p.  1095. 
Polyt.  Notizbl.,  1864,  p.  367. 

G 


82 


ANILINE  GREEN. 


to  cool,  the  liquid  thus  obtained  is  filtered  through  cloth,  in 
order  to  separate  the  greyish  blue  colouring  matter.  M. 
Lucius  adds  to  the  green  solution  from  5  to  20  parts  of 
common  salt  and  a  little  soda,  or  carbonate  of  soda,  which 
effedts  the  complete  precipitation  of  aldehyd  green. 

It  is  well  known  that  the  product  obtained  by  employing 
common  salt  and  soda  is  not  of  so  bright  a  shade  as  that 
produced  by  the  acetate,  but  now  silk  dyers  usually  pro- 
duce the  solution  of  green  themselves,  according  to  the 
specification  of  the  French  chemist  Usebe,*  taken  out  in 
the  year  1863.  His  process  consists  in  employing  150 
grammes  of  well  crystallised  sulphate  of  rosaniline,  and  450 
grammes  of  a  cold  mixture  of  three  parts  of  sulphuric  acid 
to  one  part  of  water.  When  the  red  colour  is  completely 
dissolved  he  adds  225  grammes  of  aldehyd.  After  again 
heating  and  testing  in  the  manner  mentioned  before,  the 
liquid  is  added  to  a  boiling  solution  of  450  grammes  of  sub- 
sulphide  of  sodium  in  30  litres  of  water.  The  subsulphide 
added  to  the  solution,  we  may  remark,  seems  to  be  the  prin- 
cipal agent  of  this  process ;  but  it  is  not  yet  known  whether 
this  green  is  produced  by  a  simple  reduction,  or  by  the  sub- 
stitution of  sulphur. 

A  few  years  ago  another  aniline  green  was  obtained 
together  with  Hofmann's  violet.  The  mixture  which  pro- 
duces the  violet  colour  is  heated  to  no° — 1150  C,  not  as  in 
the  production  of  violet,  for  four  to  six  hours,  but  for  a  much 
longer  time.  After  opening  the  apparatus  and  distilling  off 
the  excess  of  iodide  and  alcohol  there  is  obtained  a  mixture 
of  Hofmann's  violet  and  a  more  or  less  bluish  green  colour, 
which  may  become  even  a  greenish  blue  when  the  operation 
has  been  continued  for  a  sufficiently  long  time.  If  there  is 
too  much  violet  in  the  mass,  and  the  green  is  too  blue,  it  is 
best  to  treat  the  whole  once  more  with  the  iodide.  Some 
manufacturers  treat  their  produdt  with  iodide  until  the  whole 
or  almost  the  whole  is  transformed  into  a  green  colour,  to 
which  they  give  the  yellower  shades  by  adding  picric  acid. 

*  1863,  Schweiz.  Pol.  Zeitsch.,  1864,  p.  77.    Dingler,  vol.  173,  p.  76. 


ANILINE  GREEN. 


83 


French  and  English  manufacturers  especially  have  adopted 
this  plan,  because  the  production  of  violet  in  these  countries 
is  the  patent  monoply  of  a  few  firms.  In  Germany,  on  the 
other  hand,  violet  and  green  are  separated  by  adding  a  solu- 
tion of  some  salt  that  dissolves  the  green  and  leaves  the 
violet  colour. 

The  green  solution  got  by  one  of  these  methods  can  be 
immediately  employed  for  dyeing,  but  it  is  possible  to  pre- 
cipitate the  colouring  matter  by  adding  a  solution  of  tannic 
acid,  usually  a  decoCtion  of  gall-nuts.  By  drying  the  preci- 
pitate thus  obtained,  the  green  colour  can  be  got  as  a  red 
mass,  yielding  a  green  solution  in  water  containing  a  little 
acid.  It  has,  however,  been  found  that  the  green  liquid 
gives  a  brighter  colour  to  the  fibre  than  the  solution  of  the 
precipitate,  and  so  the  liquid  is  usually  employed  as  it  comes 
from  the  manufacturers.  It  is  very  interesting  that  the 
green  colouring  matter  when  dry  is  red,  as  the  red  colouring 
matter  forms  green  crystals. 


g  2 


CHAPTER  VII. 


ANILINE  BLACK. 

No  real  black  can  be  found  among  the  aniline  dyes.  In  all 
cases  what  is  called  black  is  really  dark  green  or  brown. 
Real  black  cannot  be  obtained  in  dyeing,  and  is  only  repre- 
sented by  amorphous  carbon ;  it  cannot  be  called  a  colour, 
but  is  rather  the  absence  of  every  colour.  Colours  produce 
their  impression  on  our  eye  by  absorbing  certain  rays  of  the 
spedtrum,  and  reflecting  others  which  thus  enter  our  eye. 
We  call  black  only  those  substances  which  absorb  all  the 
rays  and  refleft  nothing ;  from  such  a  substance  no  ray  can 
be  reflected  to  the  eye,  and  therefore  from  it  we  receive  no 
optical  impression.  A  substance  really  black  is  thus  only 
seen  in  contrast  with  other  coloured  substances.  Such  a 
black,  as  stated  above,  is  never  found  in  dyeing ;  the  black 
dyes  are  only  dark  blue,  green,  or  brown ;  and  so  in  this 
manner  may  be  explained  why,  although  a  real  black  can 
have  no  shades,  there  exists  the  well  known  difference 
between  blue  black,  greenish  black,  and  brown  black.  If 
we  succeed  in  obtaining  an  aniline  colour  so  dark  that  it 
gives  to  the  eye  the  ordinary  impression  of  black,  then  we 
may  consider  that  we  have  succeeded  in  producing  aniline 
black. 

In  the  chapter  on  Aniline  Green,  we  showed  that  a  green 
colour  might  be  obtained  by  oxidising  aniline.  Mr.  Light- 
foot,  of  Accrington,  has  obtained  in  this  way  a  very  dark 


ANILINE  BLACK. 


85 


green,  which  may  be  employed  as  a  black.  In  January, 
1863,  a  French  patent  was  granted  him  for  printing  calico 
with  aniline  black.  This  he  sold  to  the  firm  of  J.  J.  Miiller 
and  Co.,  of  Basle,  of  whom  we  have  before  spoken.  Mr. 
Lightfoot  employs  as  agents  chlorate  of  potash,  bichloride 
of  copper  (CuCl)  which  by  giving  up  chlorine  is  transformed 
into  subchloride  of  copper  (Cu2Cl),  hydrochlorate  of  aniline, 
acetic  acid  to  liberate  chloric  acid,  and  starch  paste  to 
thicken  the  mass.  The  paste  thus  made  is  used  for  printing, 
and  then  the  tissue  is  hung  up  in  oxidising  chambers,  and 
washed  with  a  weak  alkali.  The  colour  is  developed  in  the 
oxidising  chambers  by  the  mutual  reaction  of  the  chlorate 
of  potash  and  chloride  of  copper.* 

According  to  M.  Kappelin,  Lightfoot's  paste  consists  of — 

6  litres  of  water, 
850  grammes  of  white  starch, 
180        ,,         chlorate  of  potash, 
450         „  hydrochlorate  of  aniline, 

150  sulphate  of  copper. 

In  this  specification  the  sulphate  is  employed  instead  of 
the  chloride  of  copper.  The  colour  is  rendered  more  beauti- 
ful by  treating  the  printed  fabric  with  a  solution  of  bichro- 
mate of  potash. 

On  employing  the  paste  it  was  found  that  the  copper  it 
contained  was  excessively  injurious  to  certain  parts  of  the 
printing  machines  which  were  made  of  steel,  because  copper 
was  precipitated  on  this  metal,  and  thus  the  sharpness  of 
the  printing  rollers  was  affefted.  This  black  paste  was 
also  found  to  weaken  the  printed  fabric,  and  it  was  there- 
fore no  longer  employed,  although  Mr.  Camille  Koechler 
prevented  the  effefts  on  steel  by  preparing  the  paste  with- 
out a  copper  salt,  and  adding  it  afterwards  by  drawing  the 
tissue  through  a  bath  of  a  copper  salt.  This  method  was 
found  to  be  too  expensive  to  be  generally  adopted. 

Soon  after,  in  1863,  another  paste  was  introduced  by  M. 
Cordillot,  who  replaced  the  copper  salt  by  the  red  prussiate 

*  Memoirede  M.  Th.  Schneider  sur  le  noir  d'Aniline.  Bull,  de  la  Soc.  ind. 
de  Mulhouse,  part  35,  p.  176.  Dingler's  polyt.  Journ,,  vol.  176,  p.  467.  Polyt. 
Centralbl.,  1865,  p.  1,005. 


86  ANILINE  BLACK. 

of  ammQnia,  3(NH4Cy)  +  Fe2Cy3.  This  salt  is  the  ammonia 
comp6uridVd£«-tfie  common  red  prussiate  of  potash,  from 
which  it  may  be  obtained  by  adding  sulphate  of  ammonia 
to  the  solution.  By  employing  this  salt  M.  Cordillot  pre- 
vented the  steel  from  being  affefted. 

This  composition,  however,  could  not  be  generally  em- 
ployed, because  the  price  of  the  new  paste  was  very  high, 
and  because  the  temperature  at  which  black  was  produced 
could  not  very  readily  be  secured  in  the  drying  chambers  of 
printing  establishments.  Moreover  the  black  produced  by 
Cordillot's  paste  was  not  a  fine  one,  and  it  also  attracted 
moisture,  and  separated  in  large  flakes  from  the  tissue.  The 
intensity  of  this  black  was  much  less  than  that  of  Light- 
foot's  product. 

M.  Kappelin  says  that  Cordillot's  paste  is  prepared  as 
follows : — 

A  starch  paste  is  made  of  27  kilos,  of  starch,  18  litres  of 
water,  30  litres  of  gum  solution,  and  24  kilos,  of  a  solution 
of  gum  tragacanth  containing  65  grammes  of  this  gum 
per  litre.  24  litres  of  this  paste  are  mixed  with  1,350  grms. 
of  chlorate  of  potash,  and  after  allowing  to  cool,  1,900  grms. 
of  red  prussiate  of  ammonia  are  added.  This  forms  the 
paste  No.  1. 

Another  mixture,  called  No.  2,  is  composed  of  26  litres  of 
the  above  paste,  3,600  grammes  of  hydrochlorate  of  aniline, 
and  3,600  grammes  of  tartaric  acid.  The  printing  paste 
itself  is  a  mixture  of  one  part  of  No.  1,  and  two  parts  of 
No.  2. 

In  1864,  Mr.  Lauth  took  out  a  patent  for  a  method  of 
printing  aniline  black  on  calico,  and  by  this  process  cotton  is 
still  printed  with  aniline  black.  Mr.  Lauth's  paste  is  the  same 
as  that  of  Mr.  Lightfoot,  but  he  adds  the  copper  salt  in  the  form 
of  insoluble  sulphide  of  copper,  whereby  its  aftion  on  steel 
is  prevented.  After  being  printed,  this  compound,  being 
exposed  to  the  influence  of  the  atmosphere,  or  of  the  chlorate 
of  potash  in  the  paste,  is  transformed  into  a  soluble  salt,  sul- 
phate of  copper,  and  now  afts  as  the  oxidising  agent.  The  pro- 
cess is  not  expensive,  and  scarcely  weakens  the  tissues  at  all. 


ANILINE  BLACK.        /<^V  \^  ©V 1 

The  colour  produced  is  very  durable,  and [ca^pbe^ fixed  qnrthe 
fibre  at  about  400  C.  L 1  B^.>  '  " 

Mr.  Kappelin  has  made  known*  two  'different  pastes 
made  according  to  Mr.  Lauth's  principle.  In  the  first  paste 
there  is  no  chlorate  of  potash,  and  the  sulphide  of  copper  is 
oxidised  by  the  atmosphere.  It  is  obtained  by  boiling  800 
grammes  of  starch  with  5  litres  of  water,  and  adding  270 
grammes  of  sulphide  of  copper,  with  a  solution  of  500  grammes 
of  the  aniline  salt  in  1  litre  of  water. 

The  calicoes  printed  with  this  paste  should  pass  through 
the  oxidising  chamber,  and  then  be  drawn  through  a  bath  of 
water  to  which  a  small  quantity  of  ammonia  or  soda  has 
been  added.  The  hot  atmosphere  of  the  oxidising  chamber 
simply  effects  the  transformation  of  the  sulphide  of  copper 
into  the  sulphate, 

The  second  printing  paste  consists,  according  to  M.  Kap- 
pelin's  specification,  of  10  litres  of  starch  paste,  200  grammes 
of  chlorate  of  potash,  z\  kilos,  of  solution  of  gum  tragacanth, 
400  grammes  of  sulphide  of  copper,  250  grammes  of  hydro- 
chlorate  of  ammonia,  and  1  kilo,  of  some  aniline  salt,  which 
is  added  last.  The  pieces  printed  with  this  paste  are  spread 
out  for  24  hours  and  drawn  through  a  bath  containing  two 
per  cent  of  carbonate  of  soda,  after  which  they  are  vapourised 
and  at  last  washed.  The  black  thus  obtained  is  a  full  dark 
colour,  and  quite  insoluble  in  acids,  boiling  soap,  or  alkaline 
solutions.  Acids  cause  its  transformation  into  green,  but 
every  alkali  instantly  restores  the  previous  colour.  A  solu- 
tion of  bichromate  of  potash  renders  the  colour  more  intense, 
but  a  little  reddish  if  employed  in  too  large  a  quantity.  A 
concentrated  solution  of  bleaching  powder  causes  the  colour 
to  disappear,  but  it  is  reproduced  after  a  short  time  by  simple 
exposure  to  the  atmosphere.  This  patent  black  has  also 
been  bought  by  the  firm  of  J.  J.  Miiller  and  Co.,  of  Basle. 

On  the  same  principle  as  that  of  Mr.  Lauth's  method,  a 
process  of  producing  black  from  aniline  was  patented  the 
7th  June,  1864,  by  Mr.  Edw.  Jos.  Hughes,  of  Manchester. 
In  this  method  16  ounces  of  aniline  salt  are  mixed  with  4 


*  Ann.  de  Genie  civil,  Avril,  1865,  p.  237.    Polyt.  Centralbl.,  1865,  p.  1002. 


88 


ANILINE  BLACK. 


ounces  of  sulphide  of  copper  and  8  ounces  of  bichromate  of 
potash,  and  to  this  mixture  starch  paste  is  added.  The  in- 
ventor employs  this  method  of  getting  black  for  dyeing.  He 
then  precipitates  sulphide  of  iron  or  copper  on  the  fibre  by 
any  convenient  process,  and  draws  the  so-treated  tissue 
through  a  solution  of  aniline  salt  and  another  of  chlorate  of 
potash. 

Aniline  black  is  very  conveniently  employed  in  printing 
calico,  because  it  can  be  printed  together  with  most  madder 
and  steam  colours ;  but  for  dyeing  its  employment  is  still 
very  limited. 

We  must  lastly  speak  of  a  method  of  obtaining  aniline 
black,  which  though  never  employed  on  a  large  scale,  is 
yet  excessively  interesting.  This  new  process*  was  invented 
in  1865.  It  requires  no  metallic  salt,  and  the  oxidation 
to  produce  the  black  is  effected  by  pure  chloric  acid. 
From  a  mixture  of  hydrochlorate  of  aniline  and  chlorate  of 
potash,  chloric  acid  is  liberated  by  the  addition  of  hydro- 
silico-fluoric  acid,  which  forms  an  insoluble  precipitate  with 
the  potash.  This  chloric  acid  reafts  upon  the  hydrochlorate 
of  aniline,  and  effects  an  oxidation  (blackening)  of  the  aniline 
salt,  which  is  accompanied  by  evolution  of  chlorous  acid.  To 
develope  a  beautiful  intense  black  a  heat  of  from  32°to  350  C. 
is  necessary.  This  new  colour  can  be  printed  together  with 
every  other  colour,  and  as  it  contains  no  metallic  salt  it 
takes  no  colour  in  madder  baths. 

*  Bui.  de  la  Soc,  ind.  de  Mulhouse,  Aout.,  1865,  p.  345. 


CHAPTER  VIII. 


ANILINE  YELLOW. 


Under  the  trade  name  of  Aniline  Yellow  is  usually  found 
some  form  of  picric  acid  or  one  of  its  salts. 

Picric  acid  is  got  by  heating  carbolic  acid  (crystallised 
creosote  or  phenic  acid,  CI2H50,  HO)  with  nitric  acid, 
whereupon  three  atoms  of  the  hydrogen  in  the  phenic  acid 
are  replaced  by  nitric  peroxide  (N04),  so  that  the  formula  of 
picric  acid  differs  from  that  of  phenic  acid  only  by  containing 
three  atoms  of  nitric  peroxide  in  the  place  of  three  atoms  of 
hydrogen. 


Chemists  call  the  latter  compound  trinitrophenic  acid. 
With  the  solution  of  this  substance,  wool  and  silk,  and  indeed 
all  animal  fibres,  can  be  immediately  dyed  without  any -pre- 
vious preparation.  Picric  acid  is  always  obtained  when 
nitric  acid  afts  upon  animal  substances,  as  when  leather, 
silk,  or  wool  are  heated  with  this  acid.  The  action  of  nitric 
acid  on  the  skin,  whereby  it  produces  yellow  stains,  is  thus 
explained.  N 

Pure  picric  acid  is  a  crystallised  substance  well  known  to 
dyers,  and  often  employed  by  them  for  dyeing  silk  and  wool 
yellow  and  green.  It  is  only  sold  under  the  name  of  Aniline 
Yellow  when  its  properties  are  modified  by  the  addition  of 
some  foreign  materials. 


Phenic  acid. 


Picric  acid. 


go 


ANILINE  YELLOW. 


In  order  to  sell  picric  acid  as  aniline  yellow,  manufacturers 
saturate  it  with  an  alkali,  and  get  by  evaporating  the  solution 
thus  obtained  a  dark  yellow  amorphous  mass.  This  is 
offered  to  the  dyers  as  aniline  yellow ;  it  is  considerably 
cheaper  than  picric  acid,  and  also  dyes  yellow,  but  it  is  not 
so  profitable,  as  the  large  quantity  of  soda  or  other  base  em- 
ployed is  useless  for  dyeing  purposes.  Its  low  price  and  new 
name  caused  manufacturers  to  buy  this  product  without 
knowing  that  by  it  their  buildings  were  exposed  to  great 
danger.  Though  the  acid  itself  burns  quietly  when  ignited, 
in  a  similar  manner  to  pitch,  the  salts  are  excessively  explo- 
sive, and  have  already  caused  many  fatal  accidents.  Indeed, 
the  picrate  of  lead  is  so  explosive  that  it  has  been  proposed 
for  use  for  filling  shells.  The  compound  of  picric  acid  with 
soda  explodes  with  four  times  the  force  of  gunpowder,  and 
all  the  salts  of  this  acid  are  more  or  less  explosive.  Hence 
dyers  must  be  cautioned  against  buying  such  products,  and 
should  prove  them  first  by  igniting  a  small  quantity,  other- 
wise fatal  accidents  will  probably  occur.  In  Berlin  a  whole 
manufactory  was  destroyed  by  the  explosion  of  40  pounds  of 
picrate  of  soda,  and  three  men  were  killed. 

But  there  is  also  a  true  aniline  yellow  {see  page  53) 
called  chrysaniline.  To  its  solutions  in  water  a  little  acetic 
acid  is  added,  and  then  silk  and  wool  may  be  at  once  dyed 
a  beautiful  golden  yellow.  It  is  usually  sold  under  the  name 
Victoria  Orange,  and  is  a  colouring  matter  of  great  intensity 
and  brightness. 

The  German  chemist  Vogel*  has  discovered  that  by 
treating  a  solution  of  magenta  in  water  with  nitrous  acid 
(N03)  a  yellow  colouring  matter  maybe  obtained  which  dyes 
wool  and  silk  dire<5tly  of  a  yellow  colour  similar  to  that  of 
picric  acid.  Vogel  has  investigated  this  substance,  and  his 
analysis  gives  the  formula,  C40HI9N20I2.  Nitrogen  volatilises 
during  the  process,  and  the  transformation  is  probably — 

C40H19N3  +    4^0^  =   C^^N^a,  +  5N. 

Rosaniline.       Nitrous  acid.    Yellow  substance. 

*  Polyt.  Centralbl.,  1865,  p.  1072.  Jour.  Prac.  Chem.,  vol.  94,  p.  453. 
Dingler's  Polyt.  Jour. 


ANILINE  YELLOW. 


91 


By  passing  nitrous  acid  through  a  solution  of  a  rosaniline 
salt  in  water  a  brown  substance  is  formed  which  yields,  upon 
the  copious  addition  of  water,  a  yellow  solution.  The  inventor 
has  called  it  Zinaline.  It  is  with  difficulty  dissolved  by  cold 
water,  but  in  large  quantities  by  hot.  Aniline  itself  yields, 
when  treated  with  certain  metallic  oxides,  yellow  substances. 
By  treating  aniline  with  antimonic  and  stannic  acid  I  myself 
obtained  yellow  products  which  dyed  wool  and  silk.  An  ani- 
line yellow  can  also  be  obtained  by  treating  aniline  with  a 
solution  of  antimoniate  of  potash  (KO,  Sb05  +  4HO). 
M.  H.  Schiff*  describes  several  methods  of  getting  such  a 
yellow.  Latterly  Mr.  Martin  has  obtained  a  yellow  colour 
from  naphthaline.  He  took  out  a  patent  for  this,  and  sold  it 
to  Roberts,  Dale,  and  Co.,  of  Manchester.  This  yellow  is  a 
picric  acid  in  which  the  organic  radical  phenyl  is  replaced 
by  the  similar  radical  naphthyl  contained  in  the  naphthaline, 
a  substance  got  by  distilling  coal  tar,  and  the  white  crystals 
of  which  we  have  already  spoken  of.    (See  page  3). 

After  having  transformed  naphthaline  into  naphthylamine, 
in  the  same  manner  as  indicated  above  in  the  description  of 
the  change  of  benzol  into  aniline,  Mr.  Martint  adds  a  solu- 
tion of  naphthaline  in  dilute  hydrochloric  acid.  He  then 
adds  a  solution  of  nitrite  of  potash  until  a  little  of  the  liquid 
thus  obtained  gives  a  cherry-coloured  precipitate  with  alkalis. 
Nitric  acid  is  then  added,  and  the  whole  heated  slowly  to  ioo°. 
A  large  quantity  of  gas  is  given  off,  and  small  yellow  crystals 
appear  at  the  top,  which  are  collected  and  purified  by  solu- 
tion in  alcohol  and  crystallising  out  the  new  yellow  colour. 
It  is  an  acid — the  binitronaphthylic  of  the  formula — 


This  acid  and  its  salts  dye  silk  and  wool  diredtly  of  a  red- 
dish yellow  colour,  but  this  colour  cannot  be  combined  with 
red  colouring  matters  so  as  to  form  a  bright  scarlet.  It  is 
not,  therefore,  of  great  importance  in  dyeing. 

*  Annal.  d.  Chem.  u.  Phar.  vol.  127,  p.  345.  Dingler's  Polyt.  Jour.  vol. 
170,  p.  157.  Polyt.  Centralbl.,  1863,  p.  1664.  Illust.  Gewerbe  Zeitung,  1863, 
p.  386. 

j  Monatsbericht  der  Kgl.  Akad.  d.  Wissen.  zu  Berlin,  August  8,  1867. 


CHAPTER  IX. 


ANILINE  BROWN. 

As  above  shown,  the  mixture  of  the  substances  obtained  in 
the  manufacture  of  magenta  by  heating  aniline  with  oxidis- 
ing agents,  dyes  wool  and  silk  of  a  reddish  brown  shade ; 
the  higher  the  temperature  employed,  the  browner  is  the 
shade.  If  the  mass  is  only  slightly  heated,  its  solution 
dyes  of  a  dirty  red,  but  not  a  brownish  shade.  This  solu- 
tion looks  like  a  magenta  solution,  and  contains  of  course 
all  the  arsenic  acid  used  for  transforming  aniline  into 
magenta. 

Under  the  name  of  Havanna  Brown,  several  manu- 
facturers have  long  sold  the  substance  we  have  spoken  of, 
in  the  form  of  a  powder,  which  may  be  very  advantageously 
employed  by  dyers ;  only  it  must  be  carefully  used,  as  it  is 
exceedingly  poisonous.  Indeed,  this  product  is  often  used 
for  getting  red-brown  shades,  and  dyes  diredtly  the  animal 
fibre  of  silk  or  wool.  Although  it  is  possible  to  dye  brown  with 
the  above  product,  it  cannot  be  said  that  it  is  a  true  aniline 
brown,  because  it  is  only  the  mixture  of  red  and  dirty  violet 
colouring  matters  contained  in  the  rough  mass  that  pro- 
duces brown.  By  means  of  water  the  red  can  be  extracted, 
and  then  the  dyeing  power  of  this  substance  is  destroyed. 

March  17th,  1863,  M.  George  De  Laire,  of  Paris,  took  out 
an  English  patent*  for  preparing  a  brown  colouring  matter 

*  Newton's  London  Journal,  part  18,  p.  349. 


ANILINE  BROWN. 


93 


from  aniline  or  aniline  colours.  He  melts  four  parts  of 
anhydrous  hydrochlorate  of  aniline  with  one  part  of  dry 
aniline  oil.  The  temperature  is  slowly  brought  upto240°  C, 
where  it  must  stay  until  the  colour  of  the  mixture,  which 
at  first  seems  not  to  change,  is  suddenly  transformed  into 
brown.  The  whole  operation  lasts  for  two  hours,  and  may 
be  considered  over  when  yellow  vapours  begin  to  make  their 
appearance.  The  colour  thus  obtained  is  soluble  in  water, 
alcohol,  and  acids,  and  can  be  used  immediately  for  dyeing. 
To  purify  it,  it  is  sufficient  to  precipitate  with  common  salt. 
All  concentrated  saline  solutions  are  able  to  precipitate  the 
brown  colouring  matter. 

According  to  a  report  of  Mr.  Horace  Koechlin,*  to  the 
Mulhausen  Industrial  Society,  a  brown  can  be  obtained  from 
leukaniline.  Dr.  Hofmann  has  already  shown  that  by  treat- 
ing leukaniline  or  rosaniline  or  any  of  their  salts  with  oxi- 
dising agents,  brown  coloured  products  are  produced,  but  it 
was  Koechlin  who  first  sought  to  fix  these  colours  on  the 
textile  fibre.  The  inventor  obtained  his  leukaniline  from  L. 
Durand,  who  produces  it  as  follows  : — A  solution  of  magenta 
(hydrochlorate  of  rosaniline)  in  water  is  boiled  with  zinc 
powder  for  some  minutes  after  the  red  magenta  colour  has 
disappeared.  The  leukaniline  so  produced  precipitates  in 
great  part  from  the  solution,  together  with  the  oxide  of  zinc 
which  is  formed.  To  purify  it  the  precipitate  is  treated 
on  a  filter  with  alcohol,  by  which  leukaniline  is  dissolved. 
Upon  evaporation  of  the  alcohol  pure  leukaniline  is  obtained 
as  a  yellow  resinous  substance.  To  obtain  the  brown  colour 
from  leukaniline,  M.  Koechlin  uses  substantially  the  method 
employed  for  producing  black  from  aniline.  The  oxidising 
mixture  which  he  prepares  with  sulphide  of  copper  is  added 
to  the  tartrate  of  leukaniline — 

2(C40H2IN3,  HO),  (C8H40IO), 

or  to  magenta.  The  paste  thus  obtained  is  employed  for 
printing  like  the  black  paste,  and  produces  when  oxidised  in 
the  hot  chamber  a  pure  dark  brown,  which  resists  the  adtion 

*  Bull,  de  la  Societe  de  Mulhouse,  Aout.,  1865,  p.  347. 


94 


ANILINE  BROWN. 


of  acids  and  of  alkalies  and  soap  baths.  This  colour  can  also 
be  fixed  by  steam. 

This  brown  may  be  employed  on  wool  instead  of  cudbear 
brown.  The  printing  paste  consists  of  0*25  litre  of  a  ma- 
genta solution,  containing  50  grammes  of  the  colouring 
matter,  to  1  litre  of  alcohol ;  075  litre  of  gum  mucilage ; 
50  grammes  of  oxalic  acid,  and  25  grammes  of  chlo- 
rate of  potash.  When  mixed  as  above  the  paste  can  be 
used  immediately.  With  this  paste  all  shades  between  red- 
brown  and  black  can  be  produced ;  to  secure  a  red-brown, 
the  quantity  of  chlorate  of  potash  must  be  diminished,  so 
as  to  prevent  too  strong  an  oxidation.  To  give  a  yellow 
shade  to  the  same  colour  there  must  be  added  a  yellow  lac, 
free  from  protoxide  of  tin,  which  by  oxidation  would  produce 
a  reddish  brown. 

M.  Koechlin  obtained  a  brown  precipitate  by  treating  a 
solution  of  magenta  with  chlorate  of  potash  and  hydro- 
chloric acid.  This  precipitate  is  insoluble  in  water,  soluble  in 
alcohol  and  sulphuric  acid.  By  means  of  albumen  it  can 
be  fixed  on  cotton. 

The  picrate  of  ammonia — 


when  treated  with  reducing  agents  yields  a  reddish  brown 
substance  that  dyes  wool  directly. 

At  the  end  of  his  report  on  the  brown  colouring  matters 
obtained  from  tar,  M.  Koechlin  speaks  of  zinc  as  an  agent 
for  decolourising  aniline  colours  when  fixed  on  the  textile 
fibre.  The  inventor  of  this  employment  of  zinc  is  M.  Durand, 
who  prints  with  zinc  powder  (obtained  in  the  process  of  dis- 
tilling zinc),  thickened  with  starch  paste  or  gum,  as  a  cor- 
rosive paste,  on  tissues  dyed  with  aniline  red,  violet,  blue,  or 
green.  After  steaming  and  washing,  the  colour  disappears 
in  those  places  which  had  been  covered  by  the  paste.  From 
magenta,  leukaniline  is  of  course  formed  by  means  of  zinc, 
and  from  the  blue  colouring  base  triphenylleukaniline,  as 
was  before  mentioned.  Cyanide  of  potassium  produces  the 
same  effedt. 


CHAPTER  X. 


Determination  of  the  Tinctorial  Power  and  Intensity 
of  the  Aniline  Colours, 

It  is  of  the  greatest  importance  that  an  aniline  manufacturer 
should  know  the  value  of  his  products  in  comparison  with 
those  of  other  manufacturers,  especially  in  respedt  to  their 
power  of  dyeing  animal  and  vegetable  tissues. 

Usually  to  determine  the  value  of  a  dye  it  is  only  necessary 
to  determine  how  much  colour  is  requisite  to  dye  a  certain 
weight  of  wool  of  a  certain  shade,  or  how  much  wool  will  a 
certain  weight  of  colour  dye  to  the  given  shade.  The  follow- 
ing is  the  simplest  way  to  answer  these  questions  : — 

Five  decigrammes  of  the  colouring  matter  to  be  tested  are 
weighed  out  and  put  into  a  glass  retort,  and  50  cubic  centi- 
metres of  alcohol  are  added.  The  liquid  is  well  shaken  and 
heated  for  a  quarter  of  an  hour  in  a  steam  bath.  The  alcohol 
dissolves  the  colour,  and  only  a  small  quantity  of  carbon 
which  exists  in  every  aniline  colouring  matter,  especially  in 
the  blue  and  violet,  still  remains  undissolved.  The  solution 
is  allowed  to  settle,  and  then  poured  into  a  graduated  cylin- 
der. The  alcohol  evaporated  during  boiling  in  the  retort  is 
replaced  by  fresh  alcohol,  with  which  the  retort  has  been 
washed  out ;  there  is  thus  obtained  a  solution  of  1  part  of  the 
colouring  matter  in  100  parts  of  alcohol  (50  grammes  of  the 
colouring  matter  about  equalling  50  cubic  centimetres  of 
alcohol). 


96 


TESTING  ANILINE  COLOURS. 


To  answer  the  first  question,  How  much  colouring  matter 
is  requisite  to  dye  a  certain  weight  of  wool  a  certain  shade  ? 
proceed  as  follows  : — 

In  a  china  basin  a  sufficient  quantity  of  water  is  heated 
until  it  is  too  hot  to  put  the  finger  in.  Then  one  gramme 
of  fleecy  wool  is  weighed,  put  into  the  warm  water,  and 
moved  about  with  a  glass  rod  until  it  is  thoroughly  wetted. 
It  is  then  taken  out,  and  two  cubic  centimetres  of  the  colour 
solution  are  added  and  well  mixed.  The  wool  is  then  once 
more  cautiously  immersed.  It  will  now  be  dyed  by  the  solu- 
tion, and  when  all  the  colour  is  fixed,  a  fresh  portion  of  the 
solution  is  added  to  the  bath,  and  the  operation  repeated 
until  the  wool  is  dyed  of  the  desired  shade. 

The  value  of  the  colouring  matter  under  examination  is  in 
inverse  ratio  to  the  quantity  of  solution  consumed.  If  five 
cubic  centimetres  of  the  solution  of  the  standard  colour  were 
necessary  to  dye  one  gramme  of  fleecy  wool  a  certain  shade, 
and  seven  cubic  centimetres  of  the  colour  under  examination 
produced  the  same  effeft,  the  proportion  is  7  :  5  :  :  a  :  b,  a 
being  the  standard  colouring  matter,  and  b  the  colour  to  be 
tested.    Hence  the  value  of  b  is  |ths  of  that  of  a. 

The  answer  to  the  second  question,  How  much  wool  can 
be  dyed  of  a  certain  shade  by  a  certain  weight  of  colour?  is  not 
very  different  from  that  of  the  former.  A  certain  quantity  of 
the  colouring  matter  to  be  tested,  equal  to  that  of  the  standard 
employed,  is  put  at  once  into  the  dyeing  pan,  and  small  quan- 
tities of  wet  wool  are  dyed  in  the  solution  to  the  desired  shade. 
When  the  colour  in  the  bath  is  exhausted,  the  dyed  wool  is 
weighed.  Then  the  weight  of  wool  dyed  with  a  given  quan- 
tity of  the  tested  colour  (b)  is  to  the  weight  of  wool  dyed  by 
the  same  quantity  of  standard  colour  (a)  in  direct  propor- 
tion to  the  values.  If  a  dyed  1  gramme,  and  b  dyed  1*5 
grammes  of  wool,  then  the  proportion  will  be  a  :  b  :  :  1  :  1*5, 
and  thus  the  value  of  a  will  be  f  rds  of  that  of  b.  The  former 
method  is  usually  preferred,  as  the  latter  requires  more  time 
and  pains. 

A  rough  approximation  to  the  value  of  a  colouring  matter 
may  be  obtained  in  a  short  time  by  the  following  plan : — 
Take  two  bottles  of  equal  dimensions  and  of  about  25  cubic 


IDENTIFICATION  OF  ANILINE  COLOURS.  97 


centimetres  capacity,  their  horizontal  section  being  square, 
so  that  there  will  be  the  same  thickness  of  liquid  in  each 
when  the  bottles  are  placed  between  the  eye  and  a  light. 

Into  one  bottle  pour  a  solution  of  0*25  grammes  of  the 
standard  colouring  matter  dissolved  in  alcohol,  so  as  to 
make  up  25  cubic  centimetres  of  liquid  ;  call  this  A.  A 
solution  of  the  colouring  matter  to  be  tested  is  made  in 
the  same  manner,  and  poured  into  the  second  bottle ;  call 
this  B.  The  bottles  are  then  placed  side  by  side  and  the 
colour  compared.  The  darker  liquid  is  diluted  with  alcohol 
until  after  agitation  the  intensity  of  the  colour  of  the  two 
liquids  appears  the  same.  The  diluted  solution  is  then 
poured  into  a  graduated  cylinder,  and  measured  ;  the  inten- 
sities will  be  direftly  as  the  bulks  of  the  two  liquids  after 
dilution. 


To  distinguish  Aniline  Colours  from  one  another,  and 
from  similar  Colours  when  on  the  Textile  Fibre. 

For  this  purpose  M.  J.  J.  Pohl*  uses  fuming  hydrochloric 
acid. and  a  dilute  acid  consisting  of  one  part  strong  acid  to 
three  parts  of  water. 

The  effects  of  the  fuming  acid  are  observed  at  the  ordinary 
temperature  at  the  time  of  application,  after  5,  and  after  15 
minutes  ;  also  the  effeft  of  dilution  is  then  observed.  Next 
the  effects  of  the  dilute  acid  are  observed  at  first  and  after 
15  minutes.  Finally,  the  same  test  is  repeated  after  a  con- 
siderable dilution  with  water. 

The  following  table  shows  the  results  of  observations  made 
upon  the  several  aniline  colours  : — 

*  Pol.  Centralbl.,  1864,  p.  1379.    Dingler,  173,  211. 


H 


98     TABLE  FOR  THE  IDENTIFICATION  OF  ANILINE  COLOURS. 


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APPENDIX. 


REPORT 

ON  THE 

COLOURING  MATTERS  DERIVED  FROM  COAL  TAR, 

SHOWN  AT   THE    FRENCH    EXHIBITION,  1867, 

By  Dr.  A.  W.  HOFMANN,  F.R.S.,  MM.  G.  de  LAIRE, 
and  Ch.  GIRARD. 


INTRODUCTION. 

This  is  no  longer  an  age  in  which  an  industry  requires  many 
years  for  its  creation,  and  still  longer  time  for  its  develop- 
ment and  expansion. 

Jealously  guarding  the  processes  employed,  hiding  with  care 
the  raw  materials  used,  a  manufacturing  process  formerly  was 
hid  in  an  obscurity  which  had  the  effect  of  confining  a  pro- 
fitable monopoly  to  the  country  where  it  was  first  esta- 
blished. The  privileges  conceded  by  the  rulers,  a  host  of 
legislative  enactments,  general  ignorance,  and  the  special 
organisation  of  labour — all  tended,  at  a  period  anterior  to 
1789,  to  favour  this  result. 

In  our  days,  a  useful  discovery  is  scarcely  made,  or  a 
happy  application  of  one  found  out,  before  it  is  published, 
described  in  the  scientific  journals  or  other  technical  period- 
icals, and  especially  in  the  specifications  of  patents.  It 
then  becomes  the  starting-point  of  a  thousand  researches 

h  2 


100 


REPORT  ON  THE  COAL  TAR  COLOURS 


and  new  experiments,  entered  into  by  the  philosopher  in  the 
hope  of  advancing  scientific  progress,  and  by  the  manufac- 
turer with  the  expectation  of  reaping  a  material  benefit. 
From  these  multiplied  and  diverse  efforts,  these  incessant 
labours  of  an  army  of  workers,  arises  an  industry  which  has  no 
sooner  sprung  into  existence  than  it  becomes  important  and 
prosperous.  Moreover,  it  is  not  only  in  the  land  of  its  birth 
where  its  development  takes  place ;  it  extends  rapidly  in 
foreign  countries,  so  that  it  not  unfrequently  happens  that  the 
place  where  the  discovery  has  originated  is  distanced  in  the 
applications  of  it  by  neighbouring  States.  The  ocean  itself  is 
no  longer  a  barrier  between  the  nations  which  it  separates. 
New  York,  in  an  industrial  sense,  is  now  a  neighbour  of 
London,  Paris,  and  the  German  centres  of  industry. 

The  history  of  the  artificial  colouring  matters  derived 
from  coal,  abounds  in  illustrations  of  this.  It  only  dates 
from  the  end  of  1856,  and  yet  what  success  it  had  achieved 
in  the  Exhibition  of  1862  ! 

From  that  date,  owing  to  the  number,  variety,  beauty,  and 
value  of  its  products,  and  from  the  large  scale  on  which  it  was 
carried  on,  it  might  rank  with  the  largest  industries.  In  1862 
the  value  of  these  manufactures  had  risen  from  nothing  to  10 
millions  of  francs  ;  at  the  present  day  this  sum  is  trebled,  and 
still  the  products  are  much  cheaper  than  they  were  before. 
Indeed,  the  improvements  successively  introduced  into  the 
manufacture  of  the  tinctorial  products  derived  from  coal,  have 
had  the  result  not  only  of  rendering  them  more  beautiful,  but 
at  the  same  time  of  reducing  their  cost  in  such  a  manner 
that  aniline  colours  can  successfully  compete  in  price  with 
any  other  colouring  matter  of  equal  tinctorial  power  ;  so  that 
if  they  were  formerly  purchased  on  account  of  the  unexampled 
brilliancy  of  their  tints,  they  will  retain  their  importance 
owing  to  the  low  price  at  which  they  can  be  produced. 

Amongst  the  colouring  matters  which  were  already  known 
in  1862,  some  have  now  become  true  raw  materials,  from  which 
are  produced  other  colouring  matters  equally  beautiful, 
equally  rich,  and  of  no  less  importance  than  those  from  which 
they  have  sprung. 

Thus,  rosaniline  has  become  the  parent  of  a  whole  series  of 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  IOI 

colours,  and  last  of  all  of  a  green.  The  gamut  of  colouring 
matters  derived  from  aniline  is  now  complete  ;  we  have  red, 
orange,  yellow,  green,  blue,  indigo,  and  violet. 

Are  we  not  justified  in  saying  that  the  manufacture  of 
artificial  colouring  matters,  in  spite  of  the  improvements  of 
which  it  is  yet  capable,  in  spite  of  the  discoveries  which  will 
yet  enrich  it,  and  scarcely  ten  years  old,  has  emerged  from 
the  state  of  infancy,  and  become  one  of  the  most  important 
industries  of  the  age? 

But  if  the  development  of  this  new  branch  of  manufacture 
has  attained  so  high  a  point  in  so  limited  a  time,  its  pub- 
lication and  diffusion  through  the  industrial  and  commercial 
world  have  advanced  with  still  greater  rapidity.  The  first 
of  the  aniline  dyes  in  order  of  date  is  mauveine.  This  was  dis- 
covered in  the  month  of  August,  1856,  by  Mr.  W.  H.  Perkin. 
Whilst  the  inventor,  young,  and  of  ample  resources,  remained 
for  nearly  two  whole  years  before  he  could  carry  out  his  in- 
vention on  a  large  scale,  and  strove  against  the  difficulties 
which  beset  the  introduction  of  all  new  discoveries,  several 
French  manufacturers  produced  mauveine  immediately,  and 
on  a  large  scale,  by  the  aCtual  process  (or  but  slightly  modi- 
fied) which  was  revealed  to  them  by  the  English  patent. 
One  who  only  considered  the  state  of  the[-  industry  at  this 
time  in  the  two  countries,  would  have  said  that  the  invention 
belonged  to  France,  and  had  only  been  imported  into  Eng- 
land.   From  France  it  almost  at  once  spread  to  Germany. 

In  1859,  aniline  red  was  produced.  Scarcely  three  months 
after  its  production  was  commenced  at  Lyons  it  was  trans- 
planted to  Mulhouse  ;  then  crossing  the  Channel,  it  became 
established  in  England,  at  London,  Coventry,  and  Glasgow, 
and  was  not  long  before  it  was  taken  up  in  Germany. 

Aniline  blue  first  appeared  in  i860.  Less  than  a  year 
afterwards  it  took  ten  manufactories  in  Germany,  England, 
Italy,  and  Switzerland  to  produce  this  new  material. 

Whilst  the  manufacture  of  aniline  colours  thus  became 
European,  their  consumption  spread  still  further :  and  now 
could  be  observed  this  unique  faCt  in  the  history  of  commerce; 
the  West  supplied  the  East  with  colouring  matters,  sending 
its  artificial  dyes  to  the  confines  of  the  globe,  to  China,  to 


102 


REPORT  ON  THE  COAL  TAR  COLOURS 


Japan,  to  America,  and  the  Indies, — to  those  favoured  climes 
which  up  to  the  present  time  had  supplied  the  manufactories 
of  Europe  with  tinctorial  products.  This  was  a  veritable 
revolution.  Chemistry,  victorious,  dispossessed  the  sun  of  a 
monopoly  which  it  had  hitherto  always  enjoyed  :  at  the 
beginning  of  this  century,  when  mythological  language  was  in 
vogue,  it  would  have  been  said  that  Minerva  had  triumphed 
over  Apollo. 

But  it  was  not  sufficient  to  extract  colours  from  tar  and 
send  them  to  China,  it  was  necessary  to  secure  a  market  for 
them  and  get  their  acceptance  ;  and  now  occurred  a  circum- 
stance characteristic  of  this  epoch.  In  order  to  apply  these 
colours,  the  processes  being  altogether  different  from  those 
followed  by  the  Chinese,  and  their  employment  requiring  the 
assistance  of  substances  which  were  unknown  to  them,  it  was 
necessary  to  change  at  the  same  time  their  tinctorial  sub- 
stances, their  solvents,  and  their  mordants — in  a  word,  to 
undertake  the  education  of  the  Chinese  dyers.  This  difficulty 
did  not  for  a  moment  stop  the  European  manufacturer;  he  sent 
to  China  and  Japan  not  only  the  workmen  who  should  teach 
his  customers  the  way  to  apply  the  colours  with  which  he 
supplied  them,  but  also  the  chemical  products  necessary  for 
their  manipulation,  such  as  sulphuric  acid  and  absolute 
alcohol,  which  were  before  unknown  to  them.  Thus  arose 
considerable  dealings  with  the  East,  the  quantities  sold  by 
European  manufacturers  in  1864,  1865,  and  1866  amounting 
to  several  millions  of  francs. 

The  Universal  Exhibition  of  1867  shows  considerable  pro- 
gress in  all  branches  of  the  manufacture  of  artificial  colours 
since  1863.  It  should  here  be  noted  that  the  year  of  the 
English  Exhibition  was  itself  one  of  the  most  fertile  in  dis- 
coveries and  improvements. 

Almost  immediately  after  its  close  there  appeared  aniline 
green,  the  violets  of  methylic  and  ethylic  rosaniline,  and 
aniline  black,  and  at  the  same  time  science  was  able  to  dispel 
the  darkness  which  had  hitherto  enveloped  the  production  of 
the  new  colouring  matters.  If  we  wished  to  generalise,  we 
should  say  that  Exhibitions  are  not  only  of  value  in  registering 
acquired  discoveries,  but  still  more  of  inducing  and  hastening 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  I03 

the  birth  of  new  inventions.    However  this  may  be,  we  may 
here  tabulate  the  colouring  matters  mentioned  in  the  Reports 
of  the  Exhibition  of  1862  : — 
Picric  acid. 

Isopurpurate  of  potash. 

Mauveine  and  its  salts. 

Rosaniline  and  its  salts. 

Rosaniline  blue. 

Rosaniline  violet. 

Chrysaniline  (Phosphine). 

Peonine. 

Azuline. 

Emeraldine. 

Viridine. 

Azurine. 

Pseudo-alizarine. 
Some  of  these  colours  have  disappeared  from  commerce, 
if,  indeed,  it  is  certain  they  were  ever  introduced  ;  these  are 
emeraldine,  viridine,  azurine,  and  pseudo-alizarine.  The 
consumption  of  mauveine  has  diminished  considerably,  as 
well  as  that  of  the  rosaniline  violets ;  but,  on  the  other  hand, 
the  importance  of  rosaniline  and  of  triphenylic  rosaniline 
blue  has  greatly  extended.  At  that  time  aniline  black  only 
existed  in  theory,  now  it  is  one  of  the  most  valuable  of  this 
class  of  colours. 

The  following  is  a  list  of  the  colouring  matters  which,  since 
1862,  have  entered,  or  are  about  to  enter,  into  commerce,  and 
which  figured  in  the  Exhibition  of  1867 : — 

Aniline  green  from  aldehyd, 

Methylic  and  ethylic  rosaniline  violets. 

Aniline  green  from  iodide  of  methyl. 

Aniline  maroon. 

Aniline  grey. 

Aniline  black. 

Mauvaniline. 

Diphenylamine  blue. 

Chrysotoluidine. 

Naphthalic  red  (salts  of  chloroxynaphthalic  acid). 
Naphthalic  yellow  (binitro-naphthol). 


104.  REPORT  ON  THE  COAL  TAR  COLOURS 

.Amongst-- these  latter  substances  many  are  of  considerable 
/ impdrtance/^uch  as  the  new  greens,  the  violets,  and  aniline 
vy)  bl-^ck.    '  ••"  J 

'  t:  But  if  hew  colours  have  been  discovered,  the  improvement 
of  the  old  ones  has  not  been  neglected  ;  their  price  has  been 
lowered  ;  their  extreme  purity  and  beauty,  which  at  the  date 
of  the  1862  Exhibition  were  exceptional  qualities,  have  now 
become  matters  of  ordinary  production  ;  and  the  health- 
iness of  the  manufacturing  processes  have  been  considerably 
ameliorated. 

Corresponding  improvements  have  been  effected  in  the 
industry  of  the  raw  material.  In  1862,  a  large  quantity 
of  coal  tar  was  completely  lost  for  the  manufacture  of 
artificial  colouring  matters  ;  although  for  some  time  it  was 
collected  in  certain  works,  at  St.  Etienne,  for  example, 
thanks  to  the  care  and  processes  of  MM.  Pauwels  and  Knab. 
The  problem  consisted  in  transforming  the  ordinary  coke 
ovens  into  vast  gas  retorts,  which  whilst  producing  the  same 
quality  of  coke  admitted  of  the  collection  of  the  tar  and  gas  ; 
the  latter  serving  to  heat  the  ovens  themselves.  These  ap- 
paratus, which  the  limited  scope  of  our  report  prevents  us 
from  describing,  are  becoming  more  generally  adopted  ;  they 
have  already  exercised  a  notable  influence  on  the  price  of 
the  products  of  the  distillation  of  coal,  and  especially  on  the 
light  oils,  although  the  tar  is  far  from  being  collected  in  a 
complete  manner. 

In  France  three  millions  of  tons  of  coal  are  carbonised 
annually  to  supply  coke  for  metallurgical  purposes.  When 
the  process  of  MM.  Pauwels  and  Knab*  is  more  generally 
adopted  there  will  be  collected  from  this,  125  or  130 
millions  of  kilogrammes  of  tar,  which  would  yield  2  or  3 
millions  of  kilogrammes  of  light  hydrocarbons.  It  may  there- 
fore be  predicted  that  the  price  of  benzols  will  fall  still  more, 
and  that  consequently  the  cost  of  colouring  matters  derived 
from  it  will  be  reduced.  These  prices  are  at  the  present 
time  from  70  to  80  centimes  the  kilogramme  for  benzol ;  in 

*  See  La  Chimie,  by  Pelouze  and  Fremy,  vol.  ii.5  p.  884.  The  apparatus 
of  MM.  Pauwels  and  Knab  also  figure  in  the  Exhibition  of  Mines  of  the 
Loire. 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  I05 

1862  it  was  worth  3  or  4  francs  the  kilogramme;!^  Aniline 
which  then  cost  from  12  to  18  francs,  is  no\y*  wo^th  ^25 
francs,  or  3*5  francs  at  the  maximum.  Crystallised'  hy^ro-r 
chlorate  of  rosaniline  has  fallen  from  250  or  300-  frarubi'l^^ 
25  and  30  francs.  The  blue  which  was  formerly  sold  at  500 
francs  is  now  offered  at  100  francs,  and  inferior  qualities  cost 
only  30  or  40  francs.  These  figures  prove  in  a  most  con- 
vincing manner  the  enormous  progress  realised  by  the  aniline 
colour  industry  since  1862. 

This  reduction  in  price  of  the  aniline  colours  is  such  that 
all  manufacturers  who  use  colouring  matters  have  found  it 
worth  while  to  replace  their  former  tinctorial  products  by 
these  artificial  colours. 

Besides  this,  the  employment  of  these  products  has  greatly 
simplified  the  formerly  very  complicated  and  costly  opera- 
tions and  processes  of  dyeing,  so  much  so  that  an  apprentice 
can  now  obtain  as  good  shades  as  a  skilled  workman  ;  this 
facility  of  application  has  certainly  not  less  contributed  to 
the  success  of  the  coal  tar  colouring  matters,  than  the  rich- 
ness and  variety  of  their  shades. 

The  employment  of  these  magnificent  colouring  matters 
is  not  confined  to  dyeing  and  calico  printing.  They  are 
utilised  in  many  other  industries.  Their  different  applications, 
the  most  important  of  which  we  shall  rapidly  glance  over 
at  the  end  of  this  report,  have  also  contributed  to  their  de- 
velopment, although  they  only  consume  a  comparatively 
small  amount  of  these  colouring  matters. 

The  progress  which  we  are  about  to  record  in  the  industry 
of  the  coal  tar  colours  shows,  in  fadt,  that  the  probable 
development  of  the  aniline  colours  and  their  economic  and 
commercial  results,  foreseen  by  the  Reporter*  in  1852,  are 
to-day  accomplished  fadts.  Every  thing,  therefore,  leads  one 
to  imagine  that  ultimately  the  natural  will  yield  entirely  to 
the  artificial  colouring  matters. 

This  revolution,  the  influence  of  which  will  be  most  im- 
portant, since  it  will  liberate  for  the  production  of  food  many 
lands  now  employed  in  industrial  operations,  would  already 

*  International  Exhibition  of  1862.   Reports  of  the  Juries,  Class  2,  Se&ion 
A.,  p.  120. 


106  REPORT  ON  THE  COAL  TAR  COLOURS 

have  taken  place  if  the  artificial  colours  hitherto  discovered 
were  as  solid  as  their  rivals.  Less  fugitive  than  when  first 
prepared,  owing  to  the  greater  state  of  purity  in  which 
they  are  now  obtained,  they  are  still  too  dear  to  enter  largely 
into  the  dyeing  of  cloth  and  other  textures  used  for  household 
purposes.  On  reviewing  the  history  of  colouring  matters 
in  general,  we  may  be  permitted  to  hope  that  this  defeat  of 
stability  will  soon  disappear  under  the  combined  efforts  of 
science  and  industry. 

Industrial  Processes  for  the  Manufacture  of  Colouring 

Matters. 

We  propose  to  describe  successively,  and  in  a  succinct 
manner,  the  methods  which  are  actually  most  employed, 
and  are  most  advantageous  for  the  preparation  of  the  dif- 
ferent colouring  matters ;  and  we  shall  especially  dwell  upon 
the  processes  which  have  been  discovered,  improved,  or 
made  public  since  1862.  On  comparing  them  with  those 
treated  of  in  the  Reports  on  the  London  Exhibition,  a  clear 
idea  will  be  gained  of  the  changes  which  time  has  wrought. 

We  shall  commence  by  a  brief  outline  of  the  principal 
improvements  introduced  into  the  manufacture  of  the  raw 
materials  used  in  the  artificial  colour  industry. 

RAW  MATERIALS. 
I.  Benzol,  Toluol. 

These  two  hydrocarbons  are  by  far  the  most  important  in 
the  industry  now  treated  of.  They  are  extracted  from  the 
light  oils  obtained  on  the  distillation  of  the  tar  produced 
when  coal  is  carbonised  in  retorts. 

The  crude  tar  is  submitted  to  distillation,  which  is  pushed 
to  a  greater  or  less  extent  according  to  the  uses  for 
which  the  pitch  is  intended.  Three  kinds  of  pitch  are  dis- 
tinguished, only  differing  from  each  other  in  the  quantity  of 
heavy  oils  they  contain  ;  the  liquid  pitch,  which  contains  all 
the  heavy  oils;  fat  pitch,  which  contains  less;  and  dry  pitch, 
which  contains  scarcely  any. 

These  different  produces  are  employed  either  as  a  preser- 
vative and  disinfectant  paint,  for  the  preservation  of  wood, 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  107 

for  the  agglomeration  of  small  coal,  or  for  the  manufacture 
of  artificial  asphalte. 

In  the  preparation  of  these  varieties  of  pitch,  the  light 
oils  which  interest  us  most  are  always  removed.  They  con- 
sist of  a  mixture  of  a  certain  number  of  liquid  hydrocarbons, 
such  as  benzol,  toluol,  xylol,  cumol,  with  a  little  naphthalin; 
they  contain  besides  a  certain  proportion  of  substances  pos- 
sessing characters  intermediate  between  alcohols  and  acids, 
which  have  been  called  phenols,  such  as  carbolic,  cresylic,  and 
xylic  acids  or  alcohols ;  and  there  are  also  present  traces  of 
basic  substances,  such  as  aniline,  picoline,  and  leucoline. 

With  the  object  of  purifying  the  hydrocarbons  they  are 
agitated  with  dilute  sulphuric  acid,  which  removes  the  basic 
bodies,  and  then  with  a  ley  of  caustic  soda  of  sp.  gr.  1*34 
(400  Beaume),  which  dissolves  the  phenols ;  the  residue  is 
washed  several  times  in  water. 

The  treatment  of  the  mixture  obtained  in  this  manner 
varies  in  different  manufactories,  but  the  isolation  of  the 
different  bodies  is  always  effected  by  a  series  of  fractional 
distillations.  Generally  the  products  of  distillation  are 
divided  into  three  parts ;  the  first,  distilling  below  1500;  the 
second,  between  1500  and  2100 ;  and  the  third  up  to  3000.  It 
is  principally  the  first  part,  known  in  commerce  under  the 
name  of  commercial  benzol,  which  contains  the  hydrocarbons 
used  in  the  manufacture  of  colouring  matters ;  it  boils 
between  8o°  and  1200,  and  contains  the  whole  of  the  benzol, 
and  the  greater  part  of  the  toluol. 

Mansfield,*  to  whom  we  owe  the  industrial  preparation  of 
benzol,  was  the  first  who  endeavoured  to  separate  the  hydro- 
carbons from  crude  benzols,  and  obtained  products  of  a  con- 
stant boiling  point. 

The  apparatus  which  he  described  and  employed  in  1847, 
consists  of  a  boiler  surmounted  by  a  large  condenser  of  an 
ovoid  form,  surrounded  by  a  reservoir  full  of  water.  This 
condenser  carries  a  tube  which  bifurcates  in  such  a  manner 
as  to  lead  the  liquids  either  into  the  boiler,  or  into  a  refri- 
gerating worm  tube. 

*  J.  B.  Mansfield,  patent  number  11,960,  Nov.  11,  1847.  Weekly  Evening 
Meeting  of  the  Royal  Institution  of  Great  Britain,  Friday,  April  27,  1849. 


108  REPORT  ON  THE  COAL  TAR  COLOURS 


It  is  obvious,  that  in  proportion  as  the  hydrocarbons  in 
the  boiler  distil,  they  heat  the  water  in  the  reservoir  and 
fall  back  condensed,  until  the  water  has  acquired  a  tempera- 
ture equal  to  the  boiling  point  of  the  hydrocarbons ;  they 
then  distil  over.  The  boiling  point  of  pure  benzol  (8o°) 
being  below  that  of  water,  whilst  all  the  other  hydrocarbons 
contained  in  the  crude  benzols  boil  at  higher  temperatures, 
it  is  evident  that  during  the  ebullition  of  the  water  in  the 
reservoir,  almost  all  the  liquid  which  distils  over  consists  of 
benzol.  The  benzol  so  obtained  freezes  easily,  and  has  a 
boiling  point  varying  within  a  few  degrees  only  ;  by  submit- 
ting it  to  a  second  distillation,  a  still  purer  product  is 
obtained,  and  to  get  it  chemically  pure  it  is  only  necessary 
then  to  congeal  it  and  submit  the  mass  to  strong  pressure. 

M.  E.  Kopp,  in  i860,*  pointed  out  the  advantage  which 
would  be  derived  from  employing,  for  separating  the  hydro- 
carbons, the  apparatus  used  in  the  rectification  of  alcohol. 
In  1863,  M.  Th.  Coupiert  took  up  the  same  idea,  and  con- 
structed a  distillatory  apparatus  for  the  separation  of  the 
hydrocarbons.  According  to  M.  Coupier,  the  hydrocarbons, 
especially  the  benzol  and  toluol,  occurring  in  crude  benzols 
can  be  readily  isolated  by  means  of  this  apparatus. 

11.  Nitro-benzol. 

The  production  of  nitro-benzol  and  nitro-toluol  has  made 
enormous  progress  since  1862.  At  the  commencement  of 
the  aniline  industry,  this  operation  offered  serious  difficulties; 
but  the  manufacturer,  with  habitual  perseverance,  has  sur- 
mounted them ;  he  has  done  away  with  the  dangers  of  ex- 
plosion and  fire,  and  has  converted  a  perilous  operation, 
which  seemed  as  if  it  would  never  get  out  of  the  domain  of 
pure  science,  into  one  of  the  easiest  and  most  elegant  of 
manufacturing  processes.  Up  to  1862  and  1863,  nitro- 
benzol  was  only  made  in  relatively  small  quantities  at  a 
time.  Now  the  transformation  of  benzol  is  effected  on 
hundreds  of  kilogrammes  in  one  operation. 

The  operation,  which  was  originally  performed  in  vessels 
of  stone-ware  or  even  glass,  is  now  exclusively  effected  in 

*  E.  Kopp,  Moniteur  Scientifique,  t.  ii.,  liv.  86,  p.  829. 
f  Th.  Coupier's  Patent.    Paris,  April  4,  1863. 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  log 


apparatus  of  iron.  The  cast-iron  vessels  which  serve  for 
the  nitrification,  are  cylindrical,  and  of  a  capacity  of  1  or 
even  cubic  metres.  They  are  provided  with  an  agitator 
moved  by  steam.  The  upper  portion  of  the  vessel  com- 
municates on  one  side  with  a  chimney  to  lead  away  the 
nitrous  vapours,  and  on  the  other,  by  a  tube  twice  curved  in 
the  form  of  the  letter  S,  with  a  reservoir  containing  a  mix- 
ture of  nitric  and  sulphuric  acids,  the  relative  proportions  of 
which  vary  according  to  the  concentration  of  the  acids. 

The  benzol  is  introduced  all  at  once  into  the  cylinder,  but 
the  mixture  of  the  two  acids  only  comes  in  drop  by  drop 
by  the  S  tube,  which,  at  the  same  time,  serves  as  a  valve. 

Experience  has  shown  that  it  is  necessary  for  the  benzol 
to  be  attacked  as  the  acid  falls  into  the  reservoir,  so  as  to 
avoid  any  accumulation  of  nitric  acid  at  the  bottom.  This 
is  effected  by  constantly  and  regularly  agitating  the  liquid, 
and  by  warming  or  cooling  (according  to  the  season)  the 
lower  part  of  the  apparatus  where  the  reaction  proceeds. 
With  this  objeft  the  lower  portion  of  the  cylinder  is  sur- 
rounded by  a  serpentine  pipe,  through  which  may  circulate 
steam,  hot  water,  or  cold  water.  This  arrangement  permits 
of  the  reaction  being  hastened  or  moderated.  Finally,  the 
chimney  of  which  we  have  before  spoken,  carries  on  its 
upper  extremity  a  crown,  from  which  jets  of  cold  water 
constantly  flow  and  trickle  down  the  sides. 

The  conclusion  of  the  operation  is  recognised  by  the  de- 
colorisation  of  the  liquids,  which  separate  into  two  distinct 
layers.  The  acid  is  removed  by  means  of  a  stopcock  fixed 
at  the  lower  part  of  the  cylinder,  and  the  crude  nitro-benzol 
is  then  washed,  in  the  same  apparatus,  with  water  containing 
a  little  soda  in  quantity  sufficient  to  saturate  the  last  traces 
of  acid.  When  the  nitrification  has  proceeded  properly,  the 
yield  is  from  135  to  140  per  cent  of  the  benzol  employed. 

By  following  the  method  here  briefly  described  for  the 
manufacture  of  nitro-benzol,  accidents  have  become  rela- 
tively very  rare ;  and  the  workmen  are  no  longer  exposed  to 
the  nitrous  vapours,  which  some  manufacturers  condense, 
whilst  others  lead  them  direft  to  the  lead  chambers  used  in 
the  fabrication  of  sulphuric  acid. 


no 


REPORT  ON  THE  COAL  TAR  COLOURS 


III.  Aniline. 

The  transformation  of  nitro-benzol  into  aniline  takes  place 
under  the  reducing  action  of  nascent  hydrogen.  Amongst 
the  numerous  methods  which  have  been  proposed  to  effect 
this  reduction,  that  devised  by  M.  Bechamp  is  the  only  one 
adopted  in  practice.  It  consists  in  submitting  nitro-benzol 
to  the  action  of  iron  and  acetic  acid. 

The  reaction  is  effected  in  an  apparatus,  the  first  idea  of 
which  was  due  to  Mr.  Nicholson.  With  a  few  modifications 
it  is  the  one  now  adopted  by  most  manufacturers.  It  con- 
sists of  a  large  cast-iron  tubulated  retort  (at  least  i  metre  in 
diameter  and  2  metres  high),  communicating  on  one  side  by 
its  tubulus  with  a  cohobator,  and  on  the  other  side,  by  its 
neck,  with  a  refrigerator ;  a  system  of  stopcocks  allows  the 
products  of  distillation  being  turned  either  one  way  or  the 
other.  The  upper  part  of  the  retort  is  besides  furnished 
with  a  man-hole  and  an  S  tube,  which  can  at  the  same 
time  serve  as  a  safety  valve.  At  the  lower  part  is  a  hole 
closed  with  a  screw.  In  the  interior  of  the  retort  an  axis 
works,  carrying  an  agitator.  The  axis  is  turned  by  a  tube 
through  which  steam  is  brought  to  the  bottom  of  the 
apparatus. 

In  some  manufactories  the  iron  and  nitro-benzol  are 
charged  together,  whilst  the  acetic  acid  is  poured  in  in  small 
quantities  at  a  time ;  in  others,  on  the  contrary,  the  nitro- 
benzol  and  the  acetic  acid  are  introduced  together,  and  the 
iron  is  added  gradually. 

The  reduction  of  the  nitro-benzol  being  very  energetic,  and 
giving  rise  to  a  considerable  disengagement  of  vapour,  the 
vessel  communicates  during  this  operation  with  the  coho- 
bator. To  ascertain  the  end  of  the  reaction  it  is  only  neces- 
sary to  draw  off  a  small  quantity  of  the  liquid,  which  con- 
denses in  the  worm  tube  of  the  cohobator,  by  means  of  a  tap 
fixed  in  its  lower  part.  As  soon  as  the  product  dissolves  com- 
pletely in  hydrochloric  acid,  the  retort  is  put  into  commu- 
nication with  the  condenser,  when  the  aniline,  carried  over  by 
a  current  of  superheated  steam  which  is  injected  at  the 
bottom  of  the  apparatus,  is  condensed  and  collected  in  large 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  Ill 

receivers,  where  it  is  separated  from  the  water.  To  avoid 
the  loss  of  the  small  portion  of  aniline  which  is  dissolved  in 
the  water,  this  is  used  to  feed  the  boiler  which  furnishes  the 
steam.  Thanks  to  the  convenient  arrangement  of  the  new 
apparatus,  the  transformation  of  nitro-benzol  into  aniline, 
which  formerly  was  a  dangerous  and  an  unhealthy  operation, 
is  now  effected  with  great  readiness,  and  does  not  offer  the 
least  danger  to  the  workmen.  The  condensation  of  the  pro- 
ducts, which  at  one  time  escaped  and  poisoned  the  atmo- 
sphere of  the  fadtory,  now  materially  increases  the  yield  of 
aniline;  and,  in  faCt,  by  this  manner  of  working  there  is 
obtained  a  result  which  is  generally  observed  in  chemistry, 
viz.,  each  step  made  in  the  direction  of  healthfulness  is  an 
advance  in  economy. 

The  perfect  condensation  effected  by  the  cohobator  has 
also  led  to  a  considerable  reduction  in  the  quantity  of  acetic 
acid  formerly  employed,  and  to  a  consequent  diminution  in 
the  price  of  the  aniline ;  and  we  may  add  that  this  new 
apparatus,  which  admits  of  the  work  being  carried  out  on  so 
large  a  scale,  has  also  been  the  cause  of  many  other  economies 
being  effected.  Finally,  the  method  of  distilling  by  means  of 
superheated  steam  has  greatly  augmented  the  purity  of  the 
aniline  ;  it  prevents  the  formation  of  a  considerable  number  of 
secondary  products,  known  in  factories  under  the  name  of 
queues  d' aniline  (aniline  tailings),  which  are  of  no  value  in 
the  production  of  colouring  matters. 

IV.  Diphenylamine. 

Diphenylamine  and  phenyltolylamine  were  only  discovered 
in  1864 ;  they  were  found  in  the  products  of  the  distillation 
of  triphenylic  rosaniline  and  tritolylic  rosaniline.*  More 
recently,  at  the  commencement  of  1866,  a  process  has  been 
discovered  which  permits  them,  as  well  as  ditolylamine,  to  be 
obtained  easily,  and  on  the  large  scale,  t  This  process  consists 
in  heating  in  a  closed  vessel,  under  a  pressure  of  six  or  seven 

*  Hofmann,  Comptes  Rendus  de  l'Academie  des  Sciences,  1864,  ^ols.  lviii. 
and  lix. 

\  De  Laire  and  Girard's  patent.    March  21,  1866. 


112 


REPORT  ON  THE  COAL  TAR  COLOURS 


atmospheres,  and  at  a  temperature  of  about  2500,  two  parts 
of  commercial  anilineand  one  part  of  hydrochlorate  of  aniline. 

The  following  is  a  list  of  the  substances  which  we  are  now 
about  to  discuss  : — 

1.  Rosaniline  and  its  Derivatives. 

2.  Substitution  Derivatives  of  Aniline. 

3.  Derivatives  of  Phenol. 

4.  Derivatives  of  Naphthalin. 


ROSANILINE  AND  ITS  DERIVATIVES, 
i.  Manufacture  of  Rosaniline  and  its  Salts. 

The  history  of  the  discovery  of  rosaniline  was  given  in  a 
detailed  manner  in  the  Reports  of  the  Exhibition  of  1862, 
and  we  will  not  again  recur  to  it  here.  Neither  shall  we 
occupy  more  time  over  the  scientific  researches  undertaken 
with  a  view  of  clearing  up  the  obscurity  of  its  genesis,  as 
these  have  also  been  given  ;  but  it  is  impossible  for  us  to 
avoid  pointing  out  the  influence  which  these  researches  have 
had  on  the  rosanilic  industry. 

Since  the  commencement  of  the  manufacture  of  this  sub- 
stance, manufacturers  have  observed  that  the  success  of  their 
operations  depended  on  the  nature  of  the  commercial  aniline 
which  they  had  to  transform,  but  without  being  able  to  say 
very  clearly  what  were  the  causes  to  which  this  was  to  be 
attributed.  They  pointed  out  the  existence  of  a  certain 
relation  between  the  boiling  points  of  the  mixture  of  alkaloids 
employed,  and  their  yield  in  colouring  matter,  but  there  their 
science  stopped.  They  confined  themselves  to  distilling,  or, 
to  employ  the  word  adopted  in  these  factories,  to  rectifying 
their  anilines  in  such  a  manner  that  they  only  employed  pro- 
ducts distilling  nearly  between  the  same  limits. 

The  study  of  rosaniline,  the  determination  of  its  composi- 
tion, and  above  all,  the  discovery  that  this  base,  far  from 
being  a  derivative  of  aniline  alone,  owed  its  origin  to  the 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  113 

presence  of  a  certain  quantity  of  toluidine  in  commercial 
aniline,  gave  the  key  to  the  purely  empirical  operations  of  this 
industry.  From  this  day  the  rational  manufacture  of  rosani- 
line  commenced  ;  there  was  no  more  rule-of-thumb  work, 
and  no  more  uncertainties,  for  now  the  manufacturer  had 
something  definite  to  guide  him.  The  boiling  points  of 
aniline  and  toluidine  being  known,  he  soon  adopted  the  plan 
of  taking  commercial  anilines,  boiling  at  different  tempera- 
tures, and  producing  artificially  the  mixture  of  these  two  bases 
in  the  most  appropriate  proportions  for  their  transformation 
into  colouring  matters.  But  soon  the  manufacturer  was  not 
satisfied  with  the  ill-defined  products  met  within  commerce. 
He  wished  for  bodies  chemically  pure,  and  the  progress  of 
industry  soon  placed  these  at  his  disposal.  From  that  time 
unremitting  attempts  were  made  to  prepare  the  hydrocarbons 
previously  spoken  of  when  treating  of  the  raw  materials. 

Let  us,  however,  admit  that  the  reaction  by  which  rosani- 
lineis  generated,  in  spite  of  the  assistance  furnished  by  science, 
still  offers  some  difficulties.  According  to  theory,  30  per  cent 
of  aniline  and  70  per  cent  of  toluidine  ought  to  be  employed ; 
but  in  practice,  although  a  definite  conclusion  has  not  yet 
been  arrived  at  as  to  the  best  proportions  to  employ,  it  has 
nevertheless  been  ascertained  that  those  pointed  out  by  theory 
do  not  give  the  maximum  yield,  and  that  to  obtain  the  best 
result  a  larger  quantity  of  aniline  must  be  used.  The  expla- 
nation of  that,  in  our  opinion,  is  that  the  presence  of  a  certain 
proportion  of  aniline,  beyond  that  which  enters  into  the  com- 
position of  rosaniline,  facilitates  the  transformation  by  ren- 
dering the  products  of  the  reaction  more  fusible.  Whatever 
be  the  reason,  it  is  certain  that  the  liquid  which  escapes  the 
reaction  and  distils  over,  never  has  the  same  composition  as 
the  original  mixture  ;  it  consists  of  aniline,  only  containing 
traces  of  toluidine. 

Leaving  the  suggestion  we  have  just  thrown  out  for  future 
confirmation,  we  have  to  consider  the  production  of  rosani- 
line from  an  industrial  point  of  view ;  and  we  shall  enter  into 
some  details  by  reason  of  its  exceptional  importance.  Indeed, 
it  is  not  only  a  colouring  matter,  economical,  very  beautiful, 
and  easily  applied,  but  it  is  the  starting-point  of  a  host  of 

1 


ii4 


REPORT  ON  THE  COAL  TAR  COLOURS 


other  colouring  matters,  a  true  raw  material  from  which  we 
obtain  the  blue  and  violets  of  phenylic  rosaniline,  the  methylic 
and  ethylic  violets,  the  aldehyde  green,  the  iodide  of  ethyl 
green,  and  certain  yellow  brown  colouring  matters, — all 
actually  employed  more  or  less. 

Of  all  the  numerous  agents  which  at  the  outset  of  the 
aniline  colour  industry  were  recommended  for  the  commer- 
cial production  of  rosaniline,  arsenic  acid*  alone  has  main- 
tained its  position,  and  is  now  almost  exclusively  used. 

The  process  which  depends  upon  its  employment  may  be 
divided  into  three  distinct  phases  : — 

i.  The  preparation  of  the  crude  material,  or  the  transfor- 
mation of  aniline  into  a  salt  of  rosaniline.  2.  The  treatment 
in  the  wet  way  of  the  crude  material  so  obtained.  3.  The 
purification  of  the  salts  of  rosaniline  by  crystallisation. 

I.  Preparation  of  the  Crude  Material. 

Introduce  successively  800  kilos,  of  commercial  aniline 
and  1,370  kilos,  of  a  solution  containing  72  per  cent  of  an- 
hydrous arsenic  acid;  practically  corresponding  to  two  mole- 
cules of  aniline,  one  molecule  of  anhydrous  arsenic  acid,  and 
five  molecules  of  water,  t  The  retort,  of  a  capacity  of  about 
2,500  litres,  is  furnished  with  an  agitator  moved  by  steam. 
A  large  tube  parallel  to  the  axis  of  the  agitator  descends  to 
the  bottom  of  the  apparatus,  and  serves  to  conduct  steam 
into  it.  At  the  upper  part  there  is  a  man-hole,  a  valve,  and 
a  cock  which  places  the  apparatus  in  connection  with  a 
reservoir  of  warm  water ;  at  the  lower  part  are  two  taps  for 
drawing  off.  The  neck  of  the  retort  communicates  with  a 
large  serpentine  tube,  serving  to  condense  the  aniline  which 
volatilises  in  the  course  of  the  reaction.  The  temperature 
should  not  exceed  1900  or  2000;  the  operation  lasts  8  or  10 
hours ;  at  the  end  of  that  time  the  digestion  is  terminated. 
The  quantities  of  water  and  aniline  which  distil,  serve  to 
control  and  indicate  the  progress  of  the  operation ;  thus  the 
reaction  being  terminated,  there  should  be  collected  nearly 

*  Arsenic  acid,  which  formerly  was  always  prepared  by  oxidising  arsenious 
acid  by  means  of  nitric  acid,  is  now  manufactured  very  economically  bypassing 
a  current  of  chlorine  into  arsenious  acid  suspended  in  water. 

f  A  solution  of  arsenic  acid  in  these  proportions  does  not  crystallise  even 
in  the  winter. 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  115 

850  litres  of  a  mixture  of  water  and  aniline,  which,  treated 
by  chloride  of  sodium  to  effedt  their  separation,  will  give 
440  kilos,  of  aniline,  and  410  kilos,  of  water.  When  800 
litres  of  mixture  have  passed  over,  the  fire  should  be  with- 
drawn ;  the  operation  is  nearly  completed,  and  the  mass  is 
sufficiently  warm  to  admit  of  the  reaction  continuing,  and 
the  still  free  aniline  distilling  over.  During  this  time  care 
must  be  taken  to  keep  up  a  continual  movement  in  the  still 
fluid  mass  by  means  of  the  agitator.  The  quantity  of  liquid 
condensed  having  shown  that  the  reaction  is  terminated,  the 
drawing  off  must  commence  ;  the  steam-cock  is  opened,  the 
steam  rushes  violently  into  the  mass,  and  mechanically 
carries  off  with  it  the  aniline  which  may  still  be  retained  in 
the  apparatus. 

When  all  the  aniline  has  distilled  over,  gradually  introduce 
boiling  water,  so  as  to  hydrate  the  mass.  To  faciliate  this 
reaction,  the  retort  may  be  slightly  heated  again.  When  a 
thoroughly  homogeneous  mass  is  obtained,  which  happens 
in  about  an  hour's  time,  open  the  drawing-off  taps,  and  by 
the  aid  of  pipes  transfer  the  contents  to  the  vats  containing 
the  mechanical  agitators. 

To  manufacture,  in  this  manner,  2,000  kilogrammes  of 
crude  material  per  day,  four  men  are  employed.  When  once 
the  operation  is  set  going,  only  one  is  wanted  until  the  mass 
has  to  be  drawn  off.  The  three  others  are  only  required  at 
the  commencement  and  end  of  the  operation. 

The  economy  of  labour  effefted  by  this  process  is  consider- 
able, for  by  the  former  methods  it  required  at  least  ten  men 
to  do  the  same  amount  of  work ;  the  economy  of  fuel  is 
equally  great ;  besides,  the  operation  is  healthier,  there  is  no 
longer  any  transport  of  crude  material  required,  and  the 
workmen  have  not  to  handle  it  at  the  drawing  off.  This 
manipulation,  so  hurtful  and  deleterious  in  the  old  process, 
is  made  without  the  workmen  being  exposed  to  the  aniline 
vapours.  Moreover,  the  pulverisation  of  the  arsenical  mass, 
which,  in  spite  of  all  precautions,  caused  ulcerations  of  the 
nose,  lips,  and  respiratory  organs,  is  entirely  suppressed. 

Treatment  in  the  Wet  Way. — The  crude  material 
having  reached  the  vats,  is  treated  with  boiling  water,  in  the 

1  2 


Il6  REPORT  ON  THE  COAL  TAR  COLOURS 

proportion  of  300  kilos,  of  crude  material,  and  1,500  litres 
of  water  slightly  acidulated  with  3  kilos,  of  hydrochloric 
acid.  At  the  end  of  four  or  five  hours  the  solution  is  com- 
plete. It  is  run  off  and  strained  through  large  cloth  filters, 
into  vast  iron  reservoirs  of  a  capacity  of  8  or  10  cubic  metres, 
where  the  liquid  may  be  heated  by  jets  of  steam.  Each 
reservoir  therefore  contains  about  1,000  kilos,  of  crude 
material.  The  product  of  the  filtration,  in  which  there  is 
no  longer  anything  insoluble  in  water,  contains  the  aniline 
red  in  the  state  of  hydrochlorate,  arsenite,  and  arseniate  of 
rosaniline,  besides  a  large  quantity  of  arsenious  and  arsenic 
acids.  It  now  remains  to  transform  the  whole  of  the  ros- 
aniline into  hydrochlorate  of  that  base,  and  to  separate  the 
excess  of  arsenic  acid  contained  in  the  liquid. 

To  effeCt  this,  for  every  200  kilos,  of  crude  material  con- 
tained in  the  liquid,  204  kilos,  of  common  salt  are  added,  in 
small  quantities  at  a  time.  A  double  decomposition  takes 
place,  which  is  hastened  by  introduction  of  steam;  on  the  one 
hand,  hydrochlorate  of  rosaniline  is  formed,  and  on  the  other, 
arsenite  and  arseniate  of  soda.  Hydrochlorate  of  rosaniline 
is  insoluble  in  a  concentrated  saline  solution  ;  it  therefore 
separates,  and  by  virtue  of  its  low  specific  gravity  rises  to 
the  surface  of  the  liquid.  After  being  allowed  to  cool,  the 
hydrochlorate  is  collected,  and  at  the  end  of  four  days  the 
mother  liquors  are  run  into  large  reservoirs,  where  they 
deposit  a  further  quantity  of  colouring  matter,  which  they 
held  suspended.  The  hydrochlorate  of  rosaniline  thus  ob- 
tained is  washed  with  boiling  water  in  small  quantities,  so 
as  to  remove  the  common  salt  with  which  it  is  impregnated, 
and  almost  all  the  arsenical  salt  which  it  still  contains. 
For  some  applications  it  is  now  fit  for  immediate  use,  but 
it  is  preferable  to  let  it  undergo  a  crystallisation. 

Crystallisation. — The  hydrochlorate  so  obtained  is  dis- 
solved in  boiling  water,  filtered,  and  allowed  to  crystallise. 
Upon  cooling,  the  liquid  deposits  crystals  on  plates  which 
are  introduced  into  the  vats.  In  this  manner  very  beautiful 
crystals  of  the  hydrochlorate  are  obtained,  and  at  the  bottom  of 
the  crystallising  vats  a  crystalline  precipitate  is  found,  which 
maybe  used  for  the  preparation  of  the  rosaniline  blue  or  violet. 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  117 

We  may  remark,  in  conclusion,  that  in  this  process  of 
treatment  by  the  wet  way,  the  workmen  are  not  exposed,  as 
in  the  old  process,  to  acid  vapours  sometimes  mechanically 
charged  with  arsenic  or  aniline.  The  reason  of  this  is  that 
before  the  drawing  off,  almost  the  whole  of  the  unchanged 
aniline  is  removed  mechanically  by  means  of  steam,  and 
there  is  no  longer  any  ebullition  of  arsenical  compounds  in 
the  presence  of  a  concentrated  hydrochloric  acid  solution. 
In  the  present  process  liquids  nearly  neutral  are  only  operated 
on,  and  there  is  therefore  a  decided  advantage  from  a  sanitary 
point  of  view. 

II.  Preparation  of  Rosaniline. 

The  process  we  have  just  described  in  detail,  gives  ros- 
aniline in  the  state  of  hydrochlorate.  This  salt,  although 
sufficiently  pure  to  be  employed  diredlly  in  printing  and 
dyeing,  is  not  sufficiently  so  for  the  general  demand.  A  large 
number  of  applications  demand  products  of  a  superior 
quality,  containing  no  trace  of  arsenical  compounds,  and 
to  secure  this  result  the  preparation  of  free  rosaniline 
becomes  necessary;  besides,  the  preparation  of  the  derivatives 
of  this  substance  often  requires  the  employment  of  the  base 
itself,  or  at  least  of  some  other  salt  than  the  hydrochlorate. 

Many  plans  are  known  for  the  preparation  of  rosaniline 
in  the  crystalline  state  ;  they  all  depend  upon  the  facility 
with  which  salts  of  this  base  are  decomposed  by  a  solution 
of  an  alkali,  and  on  the  remarkable  property  which  rosaniline 
possesses  of  being  only  slightly  soluble  in  an  excess  of  alka- 
line liquids.  Practically,  solutions  of  caustic  soda,  lime,  and 
sometimes  even  ammonia,  are  used. 

The  hydrochlorate  of  rosaniline  dissolved  in  boiling  water 
is  decomposed  by  an  excess  of  the  alkaline  solution,  also 
boiling.  The  quantity  of  water  employed  should  be  sufficient 
to  hold  the  whole  of  the  rosaniline  in  solution.  The  ebulli- 
tion having  continued  for  several  hours,  the  liquid  must  be 
filtered  so  as  to  separate  a  little  precipitated  rosaniline. 
Upon  cooling,  the  liquid  deposits  magnificent,  almost  colour- 
less, crystals  of  rosaniline. 


Il8  REPORT  ON  THE  COAL  TAR  COLOURS 

This  process  is  simple  and  easily  executed,  but  unfortu- 
nately it  requires,  owing  to  the  slight  solubility  of  rosaniline, 
a  very  large  quantity  of  water. 

This  difficulty  was  not  long  allowed  to  baffle  manufacturers. 
It  was  found  that  by  effecting  the  decomposition  of  the  ros- 
aniline salt  under  pressure  they  could  not  only  very  con- 
siderably diminish  the  quantity  of  water  employed,  but  could 
materially  hasten  the  progress  of  the  operation. 

The  apparatus  by  which  this  transformation  is  effected  is 
a  large  closed  cauldron  of  a  capacity  of  one  or  two  cubic 
metres,  heated  by  steam,  enclosed  in  a  jacket,  and  resembling 
in  all  respeCts  the  apparatus  employed  in  dye-works  for  the 
extraction  of  colouring  matters  contained  in  wood.  The 
solution  is  effected  under  a  pressure  of  two  or  three  atmo- 
spheres, and  lasts  four  or  five  hours.  If  the  salt  of  rosaniline 
is  very  pure  the  whole  apparatus  is  allowed  to  cool,  when  by 
means  of  a  tap  placed  at  the  lower  part,  a  magma  of  crystals 
may  be  drawn  out  and  collected  on  filters.  On  the  contrary, 
if  the  salt  is  not  pure,  the  boiling  liquid  should  be  filtered  ;  to 
effeCt  this  the  apparatus  is  furnished  with  a  large  tube  des- 
cending to  the  bottom  and  communicating  at  its  other  end 
with  a  large  filtering  apparatus,  containing  a  series  of  filters 
supported  on  perforated  iron  discs.  The  pressure  of  the 
steam  in  the  cauldron  determines  the  ascent  of  the  liquid, 
which  traverses  the  filters  and  flows  into  vats,  where  the 
rosaniline  crystallises  out  on  cooling. 

ill.  Acetate  of  Rosaniline. 

The  general  mode  of  preparing  the  salts  of  rosaniline 
having  been  already  given  in  the  English  report  of  1862,  we 
will  confine  ourselves  to  a  special  description  of  the  acetate, 
the  crystallisation  of  which  requires  the  greatest  care. 

For  its  transformation  into  acetate  it  is  necessary  that  the 
rosaniline  should  be  as  pure  and  crystalline  as  possible, 
but  if  amorphous  rosaniline  is  employed,  it  should  at  all 
events  have  been  produced  from  a  well  crystallised  salt. 
Besides,  care  must  be  taken  to  free  it  completely  from  the 
excess  of  alkali  with  which  it  was  precipitated,  to  dry,  well 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  Iig 


pulverise,  and  treat  it  with  acetic  acid.  This  ought  to  be 
crystallisable  acid,  of  a  perfect  purity,  and  free  from  sul- 
phurous or  sulphuric  acids ;  calcareous  waters  must  not  be 
employed.  These  precautions  being  observed,  the  rosaniline 
as  it  comes  from  the  drying  chambers  is  to  be  introduced 
into  an  enamelled  iron  apparatus,  heated  by  steam  or  a  water 
bath.  The  acetic  acid  is  added  gradually,  and  the  mixture 
carefully  stirred  so  as  to  obtain  a  homogeneous  mass ;  the 
brick-red  colour  of  the  rosaniline  is  immediately  replaced  by 
the  green  cantharides  reflection,  characteristic  of  the  salts  of 
rosaniline.  To  facilitate  the  combination  the  mass  is  heated 
for  some  time  to  6o°  or  700 ;  boiling  water  is  then  quickly 
poured  over  the  semi-fluid  compound,  and  the  liquid  is  main- 
tained in  ebullition  for  several  minutes.  The  solution,  being 
run  into  crystallising  vats  in  a  cool  place,  and  at  a  constant 
temperature,  deposits  in  two  or  three  days  magnificent 
crystals. 
The  best  proportions  are — 

Rosaniline  100  kilos. 

Crystallisable  acetic  acid    /    .      20  ,, 

To  dissolve  these  120  kilos,  of  acetate  of  rosaniline,  240  or 
250  kilos,  of  water  are  required,  which  must  have  previously 
been  brought  to  ebullition.  In  this  manner  crystals  of 
acetate  of  rosaniline  are  obtained  nearly  equal  in  weight  to 
the  rosaniline  employed.  It  is  easy  to  understand  that  when 
the  acid  and  the  rosaniline  are  mixed,  the  temperature  should 
be  regulated,  as  acetic  acid  distils  easily  ;  the  same  precaution 
should  be  observed  when  dissolving  the  acetate  in  water,  as  a 
prolonged  ebullition  drives  off  a  greater  part  of  the  acid,  and 
gives  rise  to  subsalts  which  cannot  be  made  to  crystallise. 

Acetate  of  rosaniline  may  also  be  prepared  by  employing 
impure  salts  of  rosaniline,  such  as  the  arseniate  or  sulphate. 
Their  solution  may  be  decomposed  by  acetate  of  lead,  pro- 
ducing acetate  of  rosaniline  and  arseniate  or  sulphate  of  lead. 
Unfortunately  there  is  also  formed  a  lake  with  the  lead  and 
colouring  matter,  which  greatly  diminishes  the  yield  ;  this 
process,  therefore,  is  much  less  advantageous  than  the  former 
one. 


120 


REPORT  ON  THE  COAL  TAR  COLOURS 


IV.  Chrysaniline. 

The  salts  of  rosaniline  are  almost  always  accompanied  by 
a  yellow  colouring  matter,  chrysaniline  ;  it  often,  indeed, 
occurs  in  the  crystals,  and  when  very  abundant  hinders  crys- 
tallisation. The  mixture  of  these  two  colouring  matters  fur- 
nishes shades  redder  than  those  given  by  pure  rosaniline, 
which  always  tend  towards  violet.  It  is  known  in  commerce 
as  yellow  fuchsine. 

Two  methods  exist  for  separating  chrysaniline.  That 
most  employed  on  the  Continent  consists  of  crystallising  the 
mixture  of  the  two  bodies  from  acid  solutions.  The  greater 
part  of  the  salt  of  rosaniline  deposits,  whilst  the  chrysaniline, 
still  contaminated  with  a  little  rosaniline,  remains  dissolved 
in  the  mother  liquors  ;  these  are  first  neutralised  with  car- 
bonate of  soda,  and  then  precipitated  with  common  salt. 

In  order  to  completely  purify  the  chrysaniline,  the  precipi- 
tate is  brought  into  contact  with  zinc  and  hydrochloric  acid. 
Under  the  influence  of  nascent  hydrogen  the  rosaniline  passes 
to  the  state  of  leukaniline,  the  greater  part  of  which  dissolves. 
It  is  filtered,  and  the  treatment  is  repeated  several  times  ;  the 
salt  of  chrysaniline  is  then  dissolved  in  alcohol,  filtered,  and 
precipitated  by  means  of  an  alkali. 

In  England,  where  the  treatment  of  the  crude  material 
differs  from  that  we  have  just  described,  and  where  the  fil- 
tered solution  of  the  crude  arsenical  mass  in  boiling  water  is 
precipitated  at  once  with  lime,  the  rosaniline  separates  direft 
from  the  alkaline  solution  in  the  crystalline  state,  without 
any  admixture  of  yellow,  the  chrysaniline  remaining  with  the 
lime  precipitate. 

V.  Treatment  of  the  Residues. 

The  residues  resulting  from  the  solution  of  the  crude  mass 
in  slightly  acidulated  water  are  solid  and  pulverulent.  They 
consist  of  a  small  quantity  of  rosaniline  in  the  state  of  hydro- 
chlorate,  arsenite,  and  arseniate,  of  arsenious  acid,  of  yellow 
and  violet  colouring  matters,  and,  lastly,  of  ulmic  products. 

A  certain  quantity  of  these  residues  must  accumulate  before 
it  will  be  advantageous  to  work  them  up.  The  operation 
which  they  have  to  undergo  to  extract  the  rosaniline  from 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  121 


them  is  altogether  similar  to  that  which  we  have  already 
described  in  speaking  of  the  treatment  of  the  crude  material 
which  furnished  them,  viz.,  exhaustion  with  feebly  acid 
boiling  water,  decantation,  filtration,  and  lastly,  precipitation 
of  the  solution  with  common  salt. 

A  few  words  more  are  required  respecting  the  treatment  of 
the  residues  from  which  all  the  salts  of  rosaniline  have  been 
removed,  and  from  which  maybe  separated  the  other  colouring 
matters  which  are  always  formed  simultaneously  with  rosani- 
line. These  substances  are  three  in  number,  and  have  received 
the  names  of  violaniline,  mauvaniline,  and  chrysotoluidine. 
To  separate  these  three  bodies,  the  residue,  after  being  ex- 
hausted as  well  as  possible,  is  treated  with  an  excess  of  a  dilute 
and  boiling  solution  of  caustic  soda,  so  as  to  completely  re- 
move the  arsenical  compounds.  It  is  then  filtered,  and  the 
insoluble  mass  is  washed  with  boiling  water  and  dried,*  To 
separate  the  basic  colouring  matters  from  the  ulmic  products, 
advantage  is  taken  of  the  solubility  of  the  former  in  ether, 
benzol,  and  especially  aniline. 

The  dried  mass  is  dissolved  in  aniline  and  heated  to  ioo°; 
a  simple  filtration  separates  the  ulmic  bodies,  whilst  the  solu- 
tion contains  all  the  colouring  matters.  Upon  saturating  the 
aniline  solution  with  hydrochloric  or  acetic  acid  the  violaniline 
is  precipitated  ;  the  mauvaniline  and  chrysotoluidine  being 
soluble  in  an  excess  of  the  salt,  it  is  only  necessary  to  filter 
to  separate  the  violaniline  from  the  two  latter  substances. 
Upon  diluting  with  water  and  adding  common  salt  to  the 
liquid  the  mauvaniline  is  precipitated,  and  a  last  filtration 
separates  it  from  the  chrysotoluidine,  which  remains  in  solu- 
tion. By  saturating  the  salt  of  aniline  with  an  alkali,  and 
distilling  off  the  aniline  by  means  of  steam,  the  chrysotoluidine 
is  left  behind  in  the  retort. 

In  this  condition  the  three  new  colouring  matters  are  not 
yet  completely  pure.  Their  purification  may  be  effected  by 
successive  solutions  and  precipitations. 

The  salts  of  mauvaniline  are  soluble  in  water,  and  colour 

*  G.  de  Laire  and  C.  Girard,  French  patent,  dated  February  21,  1867, 
No.  75,101. 


122 


REPORT  ON  THE  COAL  TAR  COLOURS 


it  a  magnificent  violet  mauve  colour ;  those  of  chrysotoluidine 
give  a  yellow  solution ;  and  those  of  violaniline,  which  must 
be  dissolved  in  alcohol,  are  blue-black  with  violet  reflections. 
It  is  only  in  the  present  year  that  these  new  colouring  matters 
have  been  introduced  into  commerce. 

VI.   Treatment  of  the  Mother  \Liquors. — Regeneration 
of  the  Arsenic  Acid. 

The  term  mother  liquors  is  applied  to  the  liquids  which 
have  been  used  to  dissolve  the  crude  arsenical  product,  and 
from  which  the  colouring  matter  has  been  precipitated  either 
by  soda  or  by  common  salt.  They  generally  contain  large 
quantities  of  arsenite  and  arseniate  of  soda,  of  chloride  of 
sodium,  and  organic  salts.  It  is  unnecessary  to  remark  that 
their  composition  renders  them  dangerous,  and  that  con- 
sequently they  cause  some  trouble  to  manufacturers  of 
magenta.  From  the  commencement  of  this  industry,  which, 
in  some  manufactories,  consumes  more  than  1,000  kilos, 
of  arsenic  acid  a  day,  the  Conseils  d' hygiene  have  devoted 
attention  to  obviate  the  accidents  which  might  be  caused  by 
these  mother  liquors  being  allowed  to  flow  into  water- 
courses, brooks,  or  rivers.  The  only  method  which,  up  to 
the  present  time,  has  given,  from  a  hygienic  point  of  view,  a 
radical  solution  to  the  problem,  consists  in  evaporating 
down  the  mother  liquors.  The  expense  of  this  operation 
may  be  met  by  selling  the  mixture  of  arsenical  salts  to  the 
makers  of  arsenious  or  arsenic  acids.  If  this  plan  is  not 
adopted,  there  appears  no  other  remedy  but  reducing  the 
mother  liquors  to  as  small  a  volume  as  possible,  and  throw- 
ing them  into  the  ocean. 

Recently  attempts  have  been  made  to  regenerate  direCtly 
the  arsenic  acid  contained  in  these  liquids,  whether  free  or 
combined  with  soda.  To  effeft  this  result,  it  is  necessary 
to  evaporate  down  the  mother  liquors  with  a  quantity  of 
hydrochloric  or  sulphuric  acid,  equivalent  to  the  soda  com- 
bined with  the  arsenical  acids.  By  successive  evaporations 
and  crystallisations,  there  are  obtained,  on  the  one  hand,  the 
soda  salts  corresponding  to  the  acids  employed ;  and  on  the 
other  hand,  a  solution  of  arsenic  acid.    These  experiments 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  123 

have  only  been  carried  out  on  a  small  scale,  and  have  not 
yet  been  adopted  in  practice. 

The  difficulties  which  we  have  just  pointed  out  as  being 
due  to  the  poisonous  properties  of  arsenic,  make  it  desirable 
to  find  another  reagent  for  the  conversion  of  aniline  into 
colouring  matters.  Indeed,  in  spite  of  the  advantages  which 
it  presents  on  the  score  of  economy,  its  inconveniences  have 
prevented  it  from  entirely  replacing  the  agents  originally 
employed.  In  Germany,  for  example,  some  manufacturers, 
amongst  whom  we  may  mention  M.  Jordan,  of  Berlin,  still 
use  subnitrate  of  mercury.  From  all  that  we  have  heard, 
this  reagent,  employed  under  proper  conditions,  will  give 
equally  good  results  with  arsenic  acid,  and  by  its  use  are 
obtained  at  the  end  of  the  operation,  not  only  the  mercury 
in  the  metallic  state,  but  the  nitric  acid  in  the  form  of  nitrate 
of  lime.  The  product  sold  by  M.  Jordan  under  the  name 
of  rubine  is  free  from  arsenic,  and  is  made  in  this  manner. 

COLOURING    MATTERS    DERIVED    FROM  ROSANILINE. 

I.  Blue  and  Violet  Colours  obtained  by  Phenylation. 

Aniline  blue  figured  in  the  Exhibition  of  1862,  and  at  that 
date  was  largely  employed  in  commerce.  The  faft  that  it 
was  derived  from  rosaniline  by  the  substitution  of  three 
equivalents  of  phenyl  or  tolyl  for  three  atoms  of  hydrogen, — 
a  fa£t  which  gives  its  whole  scientific  history — has  been 
already  related  in  the  English  jury  report  of  that  date. 
Since  then  it  has  been  discovered  that  the  violet  substances 
which  are  obtained  at  the  same  time  with  the  triphenyl-  or 
tritolyl-rosaniline,  are  not  simple  mixtures  of  red  and  blue, 
but  are  well-defined  bodies,  corresponding  to  intermediate 
degrees  of  phenylation  or  tolylation.  We  propose  to  point 
out  the  rational  processes  which  permit  of  the  manufacture 
of  these  several  colours  ;  and  as  the  blue,  or  triphenyl- 
rosaniline,  is  much  the  most  important,  we  shall  commence 
by  describing  how  it  may  be  obtained. 

Blue. — In  the  preparation  of  blue,  as  in  that  of  red, 
the  nature  of  the  commercial  aniline,  and  the  proportions 
of  phenylamine  and  toluidine  which  it  contains,  exert  a 


124  :  REPORT  ON  THE  COAL  TAR  COLOURS 

consider atl?le  influence  on  the  product  obtained.  With  a  com- 
mercial aniline,  rich  in  phenylamine,  the  blue  is  principally 
cofriposed.-^f  triphenylrosaniline  ;  but  when  the  toluidine  is 
in  excess,  it  contains  more  tritolylrosaniline.  The  tri- 
phenylic  and  tritolylic  rosanilines  have  not  exactly  the  same 
solubility,  they  possess  different  shades,  and  that  of  the  tri- 
phenylic  compound  is  generally  preferred.  Experience  has 
shown,  moreover,  that  rosanil'ine  is  changed  into  Ijlue  more 
rapidly  by  phenylamine  than  by  a  commercial  aniline 
containing  much  toluidine  ;  and  the  product  is  more 
easily  purified,  and  requires  fewer  operations  to  obtain  a 
good  result  in  the  first  case  than  in  the  second.  The  aniline 
employed  must  therefore  be  as  pure  as  possible  ;  that  which 
has  escaped  aftion  in  the  preparation  of  the  red  mass,  and 
has  distilled  over,  will  do  perfectly  for  the  preparation  of  the 
blue  when  it  has  been  properly  rectified. 

Theory  gives  no  clue  to  the  kind  of  salts  of  rosaniline 
which  should  in  preference  be  employed  to  obtain  the  blue, 
but  practice  has  shown  that  this  is  not  a  matter  of  indif- 
ference. In  general,  salts  of  organic  acids  favour  the  sub- 
stitution better  than  those  of  mineral  acids.  The  acetate, 
valerianate  and  benzoate  of  rosaniline  are  the  most  generally 
employed 'of  all.  It  is  always  easy  to  effeft  the  phenylation 
on  these  salts  without  going  to  the  trouble  to  make  them 
beforehand  ;  it  suffices  to  add  to  the  mixture  of  aniline  and 
the  rosaniline  salt  taken,  either  acetate  of  soda,  valerianate 
of  soda,  &c,  or  acetic,  benzoic,  or  valerianic  acids. 

In  respeft  to  the  proportions  according  to  which  the 
aniline  should  reaft  on  the  salt  of  rosaniline,  experience  has 
shown  that  the  quantities  pointed  out  by  theory  should  be 
modified  in  order  to  ensure  regularity  of  the  operations.  In 
faft,  there  should  be  taken  three  times  the  weight  of  aniline 
which  calculation  shows  is  sufficient  for  the  complete  pheny- 
lation of  the  rosaniline  employed.  According  to  theory, 
301  parts  (1  molecule)  of  rosaniline  require  279  parts  (3 
molecules)  of  aniline,  or  100  of  rosaniline  require  92*6  of  ani- 
line to  pass  to  the  state  of  triphenylrosaniline  ;  but  in  practice 
from  2  to  3  kilogrammes  of  aniline  are  taken  for  every  kilo- 
gramme of  rosaniline. 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.^^1^5 

This  excess  of  aniline,  which  at  first  sight  sordfeis  £*\pt-' 
mous,  exerts  two  useful  actions  :  in  the  first  plate  \raamits  ^ 
of  the  formation  of  a  perfectly  fluid  solution,  an*La  Hoh^-t^ 
geneous  mass  during  the  whole  of  the  reaction  ;  and  in  the 
second  place  it  allows  a  constant  temperature  to  be  main- 
tained in  the  interior  of  the  apparatus;  and  this  can  approach 
nearer  to  the  boiling  point  of  aniline,  in  proportion  as  the 
quantity  of  this  substance  present  is  increased. 

At  the  end  of  the  reaction  there  ought  to  be  left  a  little 
more  than  half  the  aniline  originally  present.  The  manu- 
facturer who  omits  to  colled  this  will  greatly  augment  the 
cost  of  his  product.  Hence  the  necessity  of  working  in  a 
distillatory  apparatus,  or  better,  in  a  well  arranged  coho- 
bator. 

These  preliminary  observations  having  been  made,  we  shall 
proceed  to  the  description  of  the  method  of  manufacturing 
the  blue.  It  comprises  two  essentially  different  operations  ; 
in  the  first  the  rosaniline  is  phenylated,  in  the  second  the 
result  of  this  phenylation  is  purified. 

Phenylation  of  Rosaniline. — The  apparatus  employed 
consists  of  an  enamelled  iron  retort,  holding  about  20  litres, 
heated  in  a  paraffin  bath.  It  is  in  two  pieces,  the  head  and 
the  body,  united  by  pressure  screws.  The  head  of  the  retort 
should  be  tolerably  high,  to  facilitate  the  cohobation  of  the 
aniline.  Some  manufacturers  even  adapt  another  cohobator 
to  it,  in  order  to  maintain  the  same  excess  of  aniline  until 
the  phenylation  of  the  rosaniline  salt  is  complete.  The 
retort  is  furnished  with  a  mechanical  stirrer,  the  axis  of 
which  revolves  in  a  tube  through  which  steam  can  pass. 

In  this  apparatus  are  introduced  : — 

Acetate  of  rosaniline  ...     5  kilogrammes. 
Aniline  10  ,, 

Heat  is  then  applied,  and  care  is  taken,  by  observing  a 
thermometer  inserted  in  the  retort,  to  keep  the  temperature 
stationary  at  about  1900.  The  operation  lasts  about  two 
hours.  By  successive  tests  the  progress  of  the  operation  is 
watched,  and  the  moment  of  completion  ascertained.  A 
convenient  plan  is  to  introduce  a  glass  rod  into  the  retort, 


126  REPORT  ON  THE  COAL  TAR  COLOURS 

draw  it  out  and  make  a  mark  with  it  on  a  white  porcelain 
surface  ;  then  add  a  drop  of  acetic  acid  and  alcohol.  The 
mark  should  be  perfectly  blue,  and  of  a  pure  colour ;  if  it  is 
surrounded  with  a  strong  red  margin  the  operation  is  not 
yet  finished.  If  this  border,  instead  of  being  of  a  fresh 
bright  rose  colour,  has  a  reddish,  brown,  or  greenish  grey 
tint,  the  operation  has  been  carried  too  far  to  obtain  a  good 
blue.  These  essays  permit  a  skilful  operator  to  see  almost 
exaftly  how  far  the  reaction  has  proceeded,  and  allow  him 
to  stop  it  at  the  point  corresponding  to  the  desired  shade. 
In  a  well-condu6ted  operation,  and  with  correct  proportions, 
the  blue  ought  to  remain  dissolved  in  the  excess  of  aniline, 
and  the  reaction  terminated,  the  product  should  have  the 
appearance  of  a  scarcely  fluid,  but  perfectly  homogeneous, 
mass.  The  retort  is  then  raised  by  means  of  pulleys,  and 
the  screws  are  loosened  which  fasten  the  head  to  the  body, 
so  as  to  allow  the  contents  of  the  latter  to  be  poured  out. 

Purification. — The  produft  of  the  above  described  opera- 
tion undergoes  different  treatment  according  to  the  quality  of 
the  commercial  products  which  are  to  be  prepared  from  it. 
These  are  very  numerous,  but  they  may  all  be  brought  under 
three  well-defined  categories — direct  blues,  purified  blues, 
and  night  blues  (bleus  lumieres). 

Direcft  Blue. — To  prepare  this  the  treatment  of  the  crude 
mass  is  very  simple  ;  all  that  is  required  being  to  separate  the 
blue  formed  from  the  excess  of  aniline.  There  are  two  ways  to 
effect  this  ;  the  one  consists  in  driving  off  the  aniline  by  steam, 
and  the  other  in  removing  it  by  methodical  washing  with 
dilute  acids.    The  product  may  then  be  sent  into  commerce. 

Purified  Blue. — There  are  many  methods  for  preparing 
this.  The  crude  mass  resulting  from  the  phenylation  is 
mixed  with  alcohol ;  it  is  then  poured  in  a  thin  stream  into 
water  acidulated  with  hydrochloric  acid.  Hydrochlorate  of 
aniline  is  then  formed,  which  remains  dissolved  in  the  liquid 
together  with  the  excess  of  rosaniline  which  is  not  completely 
phenylated,  whilst  the  blue  is  precipitated.  This  is  then 
collected  on  a  filter  and  washed  several  times  with  boiling 
acidulated  water,  to  remove  the  brown  and  reddish  substances 
and  the  traces  of  aniline  and  rosaniline  which  may  still 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  127 

remain.  The  success  of  this  plan  depends,  it  will  be  seen, 
first  on  the  great  state  of  division  to  which  the  blue  is  brought, 
and  then  on  the  property  possessed  by  aqueous  solutions, 
containing  a  little  alcohol  but  a  large  quantity  of  aniline 
salts,  of  dissolving  all  the  foreign  matters  which  accom- 
pany it. 

Night  Blue. — The  term  night  blue  (bleu  lumiere)  is  given 
to  a  blue  entirely  free  from  violet,  and  which  preserves  its 
clear  blue  colour  in  artificial  light.  It  is  nothing  more  than 
a  perfectly  pure  salt  of  triphenylrosaniline.  To  obtain  it  a 
good  purified  blue  is  taken,  such  as  is  given  by  the  preceding 
process.  After  several  washings  with  warm  alcohol,  the 
residue  is  reduced  to  fine  powder,  dissolved  in  boiling  alcohol, 
and  the  solution  filtered.  To  the  clear  liquid  is  added  am- 
monia, or,  better  still,  an  alcoholic  solution  of  caustic  soda ; 
all  the  blue  is  precipitated  in  the  state  of  base.  When  the 
ammoniacal  or  sodic  alcohol  solution  is  quite  cold,  the  tri- 
phenylrosaniline is  collected  on  a  filter,  washed  once  or  twice 
with  boiling  water,  and  then  treated  with  the  necessary  quan- 
tity of  acid  to  form  a  salt.  It  will  be  seen  that  this  operation 
is  extremely  simple  and  gives  satisfactory  results. 

Another  more  complicated  process  has  been  employed,  and, 
indeed,  is  in  use  at  the  present  time.  The  purified  blue  is 
placed  in  enamelled  retorts  with  steam  jackets,  and  dissolved 
in  a  mixture  of  alcohol  and  hydrochloric  acid.  This  liquid  is 
brought  to  ebullition  ;  part  of  the  alcohol  distils  off,  and  it 
is  then  allowed  to  cool,  as  the  hydrochlorate  of  pure  tri- 
phenylrosaniline is  less  soluble  than  the  same  salt  of  other 
bases  which  accompany  it  ;  it  dissolves  last  and  deposits  first. 
The  liquid  is  separated  from  the  blue,  which  is  precipitated. 
On  repeating  this  treatment  several  times  a  tolerably  pure 
blue  is  obtained.  Latterly,  endeavours  have  been  made  to 
diminish  as  much  as  possible  the  quantity  of  alcohol  used  in 
the  preceding  methods  by  partially  or  entirely  replacing  it  by 
aniline  ;  the  less  volatility  of  this  substance  rendering  its  em- 
ployment more  economical.  The  mother  liquors  obtained  in 
all  the  successive  operations  of  purification  should  be  mixed 
and  carefully  preserved.    They  contain  hydrochlorate  of 


128 


REPORT  ON  THE  COAL  TAR  COLOURS 


aniline,  together  with  red,  violet,  maroon,  and  yellow  colour- 
ing matters,  and  when  benzoic  acid  has  been  employed  this 
is  also  present  in  these  liquids.  They  are  distilled  in  an 
alembic  over  lime ;  the  alcohol  comes  over  first,  then  the 
aniline,  which  is  mechanically  carried  over  by  the  vapour  of 
water,  and  there  remains  in  the  alembic  a  residue  of  benzoate 
of  lime  and  colouring  matters. 

Soluble  Blue. — Triphenylrosaniline  forms  with  sulphuric 
acid,  as  observed  by  Mr.  Nicholson,  a  true  conjugate  acid 
similar  to  sulphindigotic  acid,  very  soluble  even  in  cold  water. 
To  prepare  it  take- 
Sulphate  of  triphenylrosaniline  100  kilos. 
Common  sulphuric  acid  400  ,, 

This  mixture  is  heated  for  about  an  hour  and  a  half,  taking 
care  not  to  exceed  a  temperature  of  1400  or  1500.  It  is  then 
allowed  to  cool,  and  water  is  added,  about  eight  times  the 
weight  of  the  acid  employed.  This  must  be  mixed  gradually 
with  the  sulphuric  solution  of  the  blue,  with  constant  agita- 
tion. The  blue  then  precipitates  in  a  finely  divided  state  ;  it 
is  collected  on  a  filter  and  washed  until  the  liquid  begins  to 
run  through  of  a  blue  colour ;  this  shows  that  the  mass  is 
no  longer  acid,  for  the  blue  sulpho-conjugate  acid  is  insoluble 
in  an  acid  liquid.  It  is  then  dried  in  a  centrifugal  drying 
machine.  The  dry  precipitate  is  mixed  with  a  slight  excess 
of  ammonia  in  an  enamelled  iron  pan,  and  heated ;  the 
coloured  salt  rises  to  the  surface  as  a  golden  mass  ;  this  is 
collected,  broken  up,  dried,  and  pulverised,  after  which  it  is 
ready  for  sale. 

II.  PHENYLIC  VIOLETS. 

Phenylic  Violets. — Hitherto  we  have  only  spoken  of  tri- 
triphenylic  rosaniline  (rosaniline  blue)  ;  we  have  but  little  to 
add  respecting  the  partially  substituted  products,  mono-  and  * 
di-phenylrosaniline,  and  mono-  and  di-tolylrosaniline.  These 
have  not  yet  been  separated  or  isolated  practically,  for  want 
of  a  sufficiently  accurate  process.  The  substances  which  in 
commerce  are  known  by  the  name  of  imperial  red  violet  and 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  129 

imperial  blue  violet  are  mixtures  of  rosaniline  and  mono- 
phenylic,  diphenylic,  and  triphenylic  rosaniline,  in  the  first 
of  which  the  inferior  phenylated  compounds,  and  in  the 
second  the  higher  compounds,  are  present. 

Strictly  speaking,  no  very  distinct  process  exists  for  pro- 
ducing either  of  these  two  kinds  of  violet ;  it  is,  therefore,  not 
uncommon  for  operations  commenced  with  the  objeCt  of  ob- 
taining the  red  violet,  to  finish  by  giving  the  blue  violet.  For 
the  preparation  of  phenylic  violets  the  same  apparatus  is 
used  as  in  the  manufacture  of  blue  ;  the  mode  of  operation 
is  in  all  respeCts  similar  to  that  already  indicated  for  that 
body,  with  this  difference,  that  the  proportion  of  aniline  em- 
ployed to  phenylate  a  certain  weight  of  rosaniline  is  much 
less  when  a  violet  than  when  a  blue  is  required,  besides 
which  the  operation  lasts  a  much  shorter  time. 

The  discovery  of  secondary  monamines  of  the  phenylic  and 
tolylic  series,*  and  of  easy  processes  for  their  preparation, 
suggested  the  idea  of  manufacturing  rosaniline  blue  by  oxi- 
dising a  mixture  of  diphenylamine  and  phenyltolylamine. 
The  blue  colouring  matter  thus  formed  is  purified  by  opera- 
tions analogous  to  those  we  have  just  described.  This  pro- 
cess is  about  to  be  carried  out  on  a  large  scale. 

The  progress  effected  in  the  manufacture  of  phenylic  blue 
and  violet  is  shown  less  by  the  diminution  in  price  of  the 
products — an  important  matter  certainly,  but  one  dependent 
on  the  diminution  in  price  of  the  raw  materials — than  by  a 
considerable  improvement  in  the  shade  of  these  colours. 
This  is  due  both  to  the  improved  apparatus  employed  in  the 
manufacture,  and  also  to  the  discovery  of  the  true  nature  of 
the  reaction, — a  discovery  which  has  enabled  manufacturers 
to  devise  more  rational  processes  for  the  production  and 
purification  of  the  rosaniline  blues  and  violets. 

Violet  Substances  obtained  by  Methylation  and  Ethy- 
lation. — The  scientific  researches  which  have  established  the 
true  constitution  of  the  blue  colour,  not  only  had  the  effeCt 
already  described  of  improving  the  manufacture  of  the  special 

*  See  Girard  and  G.  de  Laire.  French  patent,  21st  March,  1866,  No. 
70,  876. 

K 


13O  REPORT  ON   THE  COAL  TAR  COLOURS 

colour,  but  also  of  leading  to  the  discovery,  and  then  to  the 
industrial  preparation,  of  new  colouring  matters  not  less 
beautiful  or  important  than  the  preceding.  We  here  see 
another  illustration  of  the  advantages  which  commerce  may 
derive  from  the  solution  of  a  purely  theoretical  problem. 
The  scientific  analysis  of  the  blue  colour,  by  demonstrating 
that  it  was  derived  from  rosaniline  by  a  hitherto  unemployed 
process  of  substitution  (phenylation  by  means  of  aniline)  im- 
mediately suggested  the  idea  of  submitting  this  base  to  the 
processes  of  substitution  ordinarily  employed  in  chemistry. 
The  iodides  of  methyl,  ethyl,  and  generally  the  iodides  and 
bromides  of  alcohol  radicals,  were  made  to  react  on  this  base, 
and  in  this  manner  were  formed  the  methylic,  &c,  rosani- 
lines,  which  are  known  in  commerce  under  the  general  name 
of  Hofmann's  violet.* 

The  first  condition  for  the  investigation  of  these  new 
reactions  was  the  production  on  a  large  scale  of  iodide  of 
ethyl  or  methyl,  bodies  long  known  as  valuable  reagents, 
but  not  yet  employed  in  manufacturing  chemistry.  The 
few  difficulties  which  were  at  first  met  with  were  quickly 
removed  by  experience,  and  now  the  preparation  of  these 
iodides  is  effected  with  no  trouble  or  danger.  Two  kinds  of 
Hofmann's  violet  are  known  in  commerce — a  red  and  a  blue 
violet.  Their  modes  of  preparation  are  practically  the  same, 
the  only  important  difference  being  in  the  proportions  of  the 
reagents  employed. 

When  operating  at  the  ordinary  pressure,  the  apparatus 
employed  is  an  alembic  heated  by  means  of  a  steam  jacket, 
and  it  should  be  made  of  copper  to  prevent  the  iodide  of 
methyl  attacking  it.  On  the  one  side  it  communicates  with 
a  condensing  worm  tube,  and  on  the  other  with  an  apparatus 
for  cohobation,  and  by  means  of  properly  arranged  taps  the 
passage  between  the  alembic  and  worm  tube  may  be  estab- 
lished or  interrupted  at  will.  A  man-hole  admits  of  the 
apparatus  being  charged  or  cleaned,  and  a  glass  tube  between 
the  alembic  and  cohobator  enables  the  condensation,  and 
consequently  the  progress  of  the  operation,  to  be  watched. 


*  Hofmann,  English  patent,  May  24,  1863.    French  patent,  July  11. 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  131 


1.  To  make  the  red  violet  take — 

Rosaniline  10  kilogrammes. 

Alcohol   100  litres. 

Iodide  of  ethyl  or  methyl    10  kilogrammes. 
Hydrate  of  potash  or  soda    10  „ 

Heat  for  about  two  hours. 

2.  For  the  blue  violet  take — 

Rosaniline  10  kilogrammes. 

Alcohol   100  litres. 

Iodide  of  methyl    ...    20  kilogrammes. 
Hydrate  of  potash  or  soda   20  ,, 

These  are  the  proportions  which  have  been  found  best  in 
practice,  but  it  is  evident  that  there  may  be  many  others. 
These  proportions  nearly  correspond,  in  the  case  of  number 
1,  to  2  molecules  of  iodide  of  ethyl  for  1  of  rosaniline,  and  in 
number  2,  to  4  molecules  of  iodide  of  methyl  for  1  of  rosani- 
line. With  iodide  of  methyl  there  are  obtained,  for  equal 
quantities,  a  blue  product,  the  solubility  of  which  in  water  is 
greater  than  when  iodide  of  ethyl  is  used.  If  the  action  of 
iodide  of  methyl  on  rosaniline  is  pushed  to  the  utmost  limits, 
a  greenish  blue  substance  is  formed,  which  has  been  lately 
employed  in  dyeing  for  the  production  of  green  shades.  We 
shall  speak  of  this  in  the  sedtion  devoted  to  the  green  deriva- 
tives of  rosaniline. 

The  colouring  matter  which  is  produced  by  this  process  is 
a  hydriodate  of  ethyl-  or  methyl-rosaniline.  To  purify  it 
distil  off  the  excess  of  alcoholic  iodides  and  alcohol,  and  then 
wash  several  times  with  boiling  water,  so  as  to  remove  the 
iodide  of  potassium  which  has  been  formed,  as  well  as  the 
excess  of  caustic  potash.  When  the  base  is  completely 
washed  it  is  dissolved  in  acid  according  to  the  salt  which  is 
desired.  The  salts  of  ethyl-  or  methyl-rosaniline  are  all  soluble 
in  alcohol,  wood  spirit,  acetic  acid,  and  mineral  acids,  and  a 
great  many,  especially  the  hydrochlorate  and  acetate,  are 
soluble  in  pure  water.  An  excess  of  common  salt,  of  sulphate 
of  soda,  or  generally  of  any  neutral  salt,  precipitates  them 
from  their  aqueous  solutions. 

The  hydriodates  of  methyl-rosaniline  and  ethyl-rosaniline 
are  almost  or  quite  insoluble  in  either  hot  or  cold  water.  At 

k  2 


132 


REPORT  ON  THE  COAL  TAR  COLOURS 


the  present  time  dyers  require  that  the  salts  furnished  to 
them  shall  be  soluble  in  water,  but  at  the  outset  of  this  in- 
dustry they  had  to  content  themselves  with  substances 
soluble  in  alcohol.  Manufacturers  of  aniline  colours  found 
it  more  profitable  to  sell  the  iodine  which  they  left  in  their 
product,  and  which  greatly  increased  its  weight,  at  the 
price  of  ethyl-rosaniline.  Iodine  was  worth  at  that  time  24 
or  25  francs  the  kilo.,  whilst  the  colouring  matter  fetched 
300  francs  the  kilo. ;  this,  therefore,  explains  why,  at  their 
first  introduction  into  commerce,  the  methylic  and  ethylic 
violets  were  generally  insoluble  in  water.  Now,  on  the  con- 
trary, care  is  taken  by  appropriate  alkaline  treatment  to  con- 
vert the  whole  of  the  iodine  into  alkaline  iodide,  from  which 
the  iodine  is  recovered. 

In  1865,  Mr.  Perkin  proposed  to  replace  the  iodides  of 
methyl  or  ethyl,  in  the  manufacture  of  violets,  by  an  alcoholic 
solution  of  bromide  of  terebene. 

We  should  here  mention  a  violet  colouring  matter  which 
was  brought  out  in  August,  1866,  and  which  figured  in  the 
Exhibition  under  the  name  of  Paris  violet.  This  violet,  by 
the  way  in  which  it  behaved  in  dyeing,  by  its  reactions,  its 
chemical  properties,  and  its  solubility  in  different  liquids, 
differed  in  no  respect  from  the  ethylic  and  methylic  violets. 
According  to  MM.  Poirier  and  Chappat,  it  is  made  in  the 
following  manner  : — In  the  first  instance  ethyl  or  methyl  is 
substituted  for  the  replaceable  hydrogen  in  aniline ;  the 
result  is  ethyl-  or  methyl-aniline,  which  is  acted  upon  by  one 
of  the  numerous  agents  (bichloride  of  tin,  for  instance),  which 
are  used  to  convert  aniline  into  rosaniline,  and  the  result  is 
Paris  violet.*  The  differences  which  exist  between  this  pro- 
cess and  that  actually  employed  in  the  manufacture  of 
methyl-  and  ethyl-rosaniline  are  not  such  as  to  preclude  the 
identity  of  the  products  prepared  by  either  method. 

The  process  patented  by  MM.  Poirier  and  Chappat  is,  as  will 
be  observed,  double.  It  includes,  in  the  first  place,  the  pre- 
paration of  ethylic  and  methylic  derivatives  of  aniline,  and, 
in  the  second  place,  the  transformation  of  these  secondary 

*  Poirier  and  Chappat.  patent  of  June  16,  1866. 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  I33 


monamines  into  violet  colouring  matters.  The  method 
which  they  have  adopted  to  produce  methyl-  and  ethyl- 
aniline  is  that  pointed  out  by  M.  Berthelot*  for  producing 
generally  the  monamines  of  the  alcohol  radicals.  This  is  a 
new  illustration  of  the  introduction  of  scientific  processes 
into  manufactures;  and,  what  is  very  remarkable,  of  all  the 
methods  which  have  been  employed  for  the  preparation  of 
the  methylic  and  ethylic  alkaloids,  this,  which  seems  the  least 
practicable  in  the  laboratory,  is  the  only  one  which  is  em- 
ployed commercially. 

The  publication  of  these  processes  gave  rise  to  a  reclama- 
tion on  the  part  of  M.  Lauth,  t  who  pointed  out  that  in  Feb- 
ruary, 1861,  M.  E.  Koppt  called  the  attention  of  chemists  to 
the  more  and  more  violet  tints  of  the  methyl  and  ethyl  sub- 
stitution products  of  aniline  red,  and  that  he  himself  §  had 
obtained  in  the  July  of  the  same  year,  a  very  beautiful  violet 
by  the  oxidation  of  methyl-aniline,  by  means  of  the  reagents 
employed  to  transform  aniline  into  magenta. 

III.  Aniline  Green. 

There  are  two  kinds  of  aniline  green,  one  obtained  by 
the  aCtion  of  aldehyd  on  the  sulphuric  solution  of  rosani- 
line,  and  another  resulting  from  the  aCtion  of  iodide  of  methyl 
on  rosaniline.  We  propose  to  describe  each  in  chronological 
order. 

Aldehyd  Green. — This  green  was  patented  in  October, 
1862,  by  M.  Usebe.  Its  discovery  some  months  before  is  due 
to  a  combination  of  circumstances  sufficiently  curious  to  de- 
serve recording,  although  such  occurrences  are  not  unex- 
ampled in  the  history  of  scientific  progress.  The  following 
account  of  this  discovery  was  given  to  the  reporters  by  the 
author  himself. 

A  dyer,  like  all  others  of  his  craft  at  that  time,  was  busily 
occupied  experimenting  with  the  aniline  dyes.  Amongst 

*  Berthelot,  on  the  production  of  ethylic  and  methylic  alkaloids  by 
chloride  of  ammonium.  Ann  de  Chim.  et  de  Phys.,  3rd  series,  vol.  xxxviii., 
p.  63. 

f  Lauth,  Moniteur  Scientifique,  December,  1866,  p.  1082. 

I  E.  Kopp,  Comptes  Rendus,  vol.  Hi.,  p.  363. 

§  Lauth,  Moniteur  Scientifique,  July,  1861,  p.  336. 


134 


REPORT  ON  THE  COAL  TAR  COLOURS 


other  things  he  tried  a  reaftion  which  had  been  described  by 
M.  Lauth,  at  the  end  of  1861,  viz.,  that  of  aldehyd  on  a 
sulphuric  solution  of  aniline  red.  In  this  rea&ion,  a  sub- 
stance is  produced  which  gives  to  solutions  an  extremely 
evanescent  blue  colour.  M.  Lauth  had  given  up  all  idea  of 
utilising  this  blue  colour  in  practice  ;  and  M.  Cherpin  en- 
deavoured to  fix  the  same  colour  on  silk  or  wool  with  similar 
want  of  success.  His  attempts,  although  fruitless,  were 
incessantly  renewed,  exhausting  his  purse,  but  not  his 
patience.  One  day,  however,  discouraged  at  the  want  of 
success  attending  some  recent  experiments  on  which  he  had 
founded  great  hopes,  he  was  on  the  point  of  relinquishing 
the  attempt  at  conquest  over  this  fugitive  blue,  when  the 
idea  struck  him  to  confide  his  troubles  to  an  old  friend,  a 
photographer.  A  trouble  shared  is  a  trouble  halved,  says 
the  proverb  ;  Cherpin  proceeded  to  test  this  saying,  and  ex- 
perienced the  reward  of  his  perseverance  and  his  confidence 
in  the  consolations  of  friendship.  He  found  his  photographic 
friend,  and  confided  to  him  the  history  of  all  his  hopes,  his 
experiments,  and  his  fruitless  results. — "  Fix  the  blue  ?" 
said  his  friend.  "  Is  that  the  only  difficulty  ?  Why  it's 
the  easiest  thing  in  the  world  !  Have  you  tried  hyposulphite 
of  soda?" — "Hyposulphite  of  soda?  Mon  Dieu,  no!  Do 
you  think  it  will  fix  my  colour?" — "Of  course  it  will.  Don't 
you  know  that  hyposulphite  of  soda  is  the  fixing  agent  par 
excellance,  and  that  when  we  want  to  fix  anything  in  photo- 
graphy, that  is  the  substance  we  always  employ  ?" 

Happy  he  who  possesses  faith  !  Cherpin  tried  hyposul- 
phite of  soda,  and  his  joy  and  admiration  of  the  chemical 
knowledge  of  his  friend  may  be  imagined  when  he  saw  his 
blue  colour  metamorphosed  into  a  splendid  green,  this  time 
perfectly  stable.  It  is  scarcely  necessary  for  us  to  add,  that 
the  mode  of  adtion  of  hyposulphite  of  soda  in  this  case,  is 
entirely  different  from  its  photographic  action,  and  that  it 
would  be  quite  impossible  to  predict  the  one  by  knowing  the 
other. 

This  anecdote  contains  a  moral.  It  shows,  in  our  opinion, 
not  the  result  of  chance,  for  that  is  common  to  all  the  world, 
for  where  is  the  discovery  to  which  chance  has  not  more  or 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  I35 


less  contributed  ?  but  it  shows  the  power  of  the  will,  the  power 
of  perseverance.  Chance  only  favours  two  kinds  of  persons  ; 
those  sufficiently  instructed,  or  endowed  with  talents  eminent 
enough,  to  observe  it,  to  seize  it,  and  to  profit  by  it  5  and 
those  who,  by  patience,  perseverance,  and  the  power  of  their 
will,  force  it  in  time  to  become  useful  to  them. 

M.  Usebe  improved  upon  the  discovery  of  M.  Cherpin, 
and  rendered  it  industrially  available.  The  green  produced 
by  this  process  is  very  beautiful,  and  has  been  rapidly 
adopted  in  commerce  for  dyeing  and  printing ;  but  in  spite 
of  the  efforts  of  M.  Usebe,  and  especially  of  M.  Muller,  of 
Bale,  it  has  not  yet  become  the  basis,  of  a  large  chemical 
manufacture,  like  aniline  blue  or  red. 

The  explanation  of  this  is,  that  after  the  colour  has  been 
prepared  for  a  certain  time,  it  loses  its  freshness,  and  ulti- 
mately becomes  destroyed.  Most  dyers,  therefore,  prepare 
the  green  for  themselves,  and  only  make  it  in  proportion  to 
their  immediate  requirements. 

Each  dyer  has  a  formula  which  he  thinks  gives  the  best 
results.    The  following  proportions  are  much  employed : — 

Aniline  red   300  grammes. 

Mixture  of  3  parts  of  sulphuric  acid 

and  1  of  water   900  ,, 

Aldehyd   450 

The  aldehyd  should  be  added  gradually  to  the  cold  solu- 
tion of  sulphate  of  rosaniline,  and  when  it  is  all  mixed,  the 
whole  is  heated  on  a  water  bath  until  the  mass  is  completely 
homogeneous.  From  time  to  time  a  drop  of  the  mixture  is 
taken  out  on  a  glass  rod,  and  thrown  into  slightly  acidulated 
water.  When  a  fine  blue  solution  is  obtained  the  readtion 
is  arrested.  The  whole  is  then  poured  into  60  litres  of  boil- 
ing water,  containing  in  solution  900  grammes  of  crystal- 
lised hyposulphite  of  soda  ;  the  mixture  is  boiled  for  a  few 
minutes  with  a  current  of  steam,  and  filtered.  All  the  green 
remains  in  solution,  whilst  a  kind  of  greyish  blue  colouring 
matter  is  collected  on  the  filter.  This  green  liquid,  prepared 
as  above  described,  constitutes  an  excellent  dye-bath  for  silk 
or  wool,  provided  it  is  used  at  once. 

Some  makers  of  aniline  green  employ  slightly  different 


136 


REPORT  ON  THE  COAL  TAR  COLOURS 


proportions.  They  dissolve  1  kilo,  of  pure  crystallised  sul- 
phate of  rosaniline,  in  2  kilos,  of  sulphuric  acid  of  sp.  gr. 
1*63,  at  66°  B.,  mixed  with  500  grammes  of  water.  When 
the  solution  is  homogeneous  they  add  4  litres  of  a  concen- 
trated alcoholic  solution  of  aldehyd.  At  the  end  of  half  an 
hour  the  reaction  is  nearly  terminated  ;  the  mixture  is  then 
poured  into  100  litres  of  water,  containing  4  kilos,  of  crys- 
tallised hyposulphite  of  soda,  the  whole  is  boiled  for  ten 
minutes  and  filtered,  to  separate  the  greyish  blue  from  the 
green  which  passes  through  with  the  liquid.  To  precipitate 
the  green,  acetate  of  soda  and  tannin  may  be  employed ;  a 
precipitate  is  thus  produced,  which  may  be  dried,  but  it  is 
more  commonly  sold  in  the  form  of  paste  :  this  is  only  used 
in  printing. 

The  greatest  uncertainty  still  exists  as  to  the  chemical 
constitution  of  aniline  green.  We  are,  however,  justified  in 
hoping  that  this  will  soon  cease  to  be  the  case  ;  aniline 
green  is  now  a  commercial  substance,  manufactured  on  a 
large  scale,  and  is  becoming  more  and  more  pure  every  day. 
After  having  presented  to  science  a  problem,  without  fur- 
nishing the  data  necessary  for  its  resolution,  manufacturing 
industry  is  working  to  fill  up  the  gap,  and  everything  leads 
us  to  anticipate  a  successful  result.* 

Iodide  of  Ethyl  Green. — When  methylic  and  ethylic 
violets  are  treated  with  boiling  water,  a  greenish  blue  sub- 
stance remains  in  solution  ;  the  liquid  is  mixed  with  car- 
bonate of  soda,  which  precipitates  a  little  violet,  whilst  the 
green  remains  dissolved.  To  extract  this,  a  concentrated 
solution  of  picric  acid  is  added  to  the  solution,  when  a  green 
colouring  matter  is  precipitated  ;  this  is  collected  on  a  filter, 
and  washed  two  or  three  times  with  cold  water.  Manu- 
facturers of  artificial  colours  have  only  commenced  to  intro- 
duce this  new  green  substance  commercially,  since  the 
year  1866.  It  is  generally  sold  in  powder,  and  is  pre- 
ferred in  dyeing  to  the  green  prepared  with  aldehyd. 
Nothing  is  yet  known  as  to  its  chemical  composition. 

*  Dr.  Quesneville  informs  us  that  since  the  publication  of  this  report 
MM.  Girard  and  de  Laire  have  obtained  aniline  green  in  the  crystallised 
state,  giving  the  most  brilliant  results  in  dyeing. 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  I37 

SUBSTITUTION  DERIVATIVES  OF  ANILINE. 

I.  Mauveine  and  its  Derivatives. 

The  history  of  the  discovery  of  mauveine,  and  the  dif- 
ferent processes  for  its  manufacture,  have  already  been  given 
in  the  Reports  of  the  Exhibition  of  1862.  All  that  now 
remains  to  record  is,  that  since  that  date,  its  composition  has 
been  determined. 

Blue. — Attempts  have  been  made  to  prepare  substitution 
products  from  mauveine.  Upon  submitting  it  to  the  action 
of  aniline,  under  the  same  conditions  employed  to  obtain 
triphenylic  rosaniline,  a  blue  colour  is  produced,  but  one 
whose  tint  is  neither  so  rich  nor  agreeable,  and  which  has 
not  been  adopted  in  commerce. 

Grey. — Upon  treating  with  aldeyhd  a  sulphuric  solution 
of  mauveine,  a  colouring  matter  is  produced,  which  dyes 
fabrics  a  flaxen  grey.  The  mode  of  applying  this  substance 
is  very  easy ;  but  unfortunately,  its  price  is  still  very  high,  on 
account  of  the  value  of  mauveine,  which  is  still  100  francs  the 
kilo.  This  would  prevent  the  derivatives  of  the  mauveine 
series  from  acquiring  an  importance  at  all  comparable  to 
that  of  the  rosaniline  series,  even  if  their  shades  were 
equally  perfedt,  which  they  are  not. 

The  constitution  and  the  composition  of  aniline  grey  are 
as  yet  unknown,  as  it  has  not  yet  been  the  objedt  of  any 
scientific  study.  M.  J.  Castelhaz  has  taken  out  a  patent 
for  the  following  preparation  : — Dissolve  10  kilos,  of  mau- 
veine in  paste,  in  n  kilos,  of  sulphuric  acid,  at  66°  B. 
After  having  added  to  the  mixture  6  kilos  of  aldehyd,  allow 
it  to  stand  four  or  five  hours.  Then  throw  the  mass  on  a 
filter ;  the  grey  passes  through,  and  may  be  precipitated  by 
a  salt.  It  is  purified  by  solution  and  precipitation  repeated 
two  or  three  times. 

II.  Aniline  Maroon  and  Brown. 

Many  brown  and  maroon  colouring  matters  exist  which 
are  made  from  commercial  aniline,  but  their  mode  of  pre- 
paration is  still  obscure.  The  first  was  pointed  out  by  Mr. 
Perkin  in  1863,  as  a  secondary   product  of  the  reaction 


I38  REPORT  ON  THE  COAL  TAR  COLOURS 

which  produces  mauveine  ;  a  second  results  from  the  aftion 
of  an  oxidising  agent  on  ditolylamine  ;  *  and  a  third  is  ob- 
tained by  the  aftion  of  hydrochlorate  of  aniline  on  a  salt  of 
rosaniline.  This  last  having  proved  of  most  commercig.1 
importance,  we  will  give  the  mode  of  its  preparation^ 

A  mixture  of  4  parts  by  weight  of  hydrochlorate  of  aniline, 
and  1  part  of  a  salt  of  rosaniline  and  a  mineral  acid  (the 
hydrochlorate,  sulphate,  or  phosphate,  gives  the  best  results), 
is  heated  to  2400,  and  the  mass  maintained  in  ebullition 
until  the  colour,  which  is  at  first  of  a  beautiful  red  violet, 
and  apparently  undergoing  no  change,  suddenly  passes  to 
maroon.  The  operation  lasts  for  one  or  two  hours,  and  its 
approaching  termination  is  known  by  the  appearance  of 
yellow  vapours,  which  condense  in  the  cold  parts  of  the 
apparatus.  The  maroon  substance  thus  obtained  is  soluble 
in  alcohol,  ether,  benzol,  and  acetic  acid,  and  it  is  precipitated 
from  its  solutions  by  alkalies  and  neutral  salts  in  concen- 
trated solution.  These  properties  enable  it  to  be  purified  ; 
it  can  then  be  employed  in  dyeing,  and  gives  very  beautiful 
shades  on  silk  and  leather. 

III.  Aniline  Black. 

Up  to  the  present  time,  aniline  black  is  not  a  definite 
chemical  compound,  a  substance  which  can  be  produced  in 
the  isolated  state ;  it  is  not  even  a  produdt  which  has 
assumed  a  commercial  form.  It  is  necessary  to  be  produced 
direft  on  the  fabric,  and,  if  we  except  some  quite  recent 
endeavours  to  apply  it  to  dyeing,  it  has  hitherto  been  used 
only  in  printing.  Aniline  black  therefore  scarcely  enters 
into  our  province,  since  it  is  not  the  object  of  a  chemical 
industry  properly  so-called  ;  nevertheless,  its  importance  in 
the  calico  printing  trade,  and  its  probable,  almost  certain, 
application  to  dyeing,  will  not  allow  us  to  pass  it  over  in 
silence. 

Aniline  black  was  introduced  into  commerce  towards  the 
end  of  1862,  and"patented  in  France,  in  January,  1863,  by 
Mr.  John  Lightfoot,  of  Accrington.    It  may  be  said  to  have 

*  Girard  and  de  Laire,  Comptes  Rendus,  vol.  lxxiii.,  p.  964. 
f  Girard  and  de  Laire,  Patent  of  March  23,  1863. 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  139 

actually  existed  since  the  year  i860 ;  it  was  indeed  produced 
by  the  process  described  by  Messrs.  Crace  Calvert,  Charles 
Lowe,  and  Samuel  Clift,  for  obtaining  dark  blue  and  green 
colouring  matters. 

The  process  patented  by  Mr.  Lightfoot  has  this  peculiarity, 
that  the  black  colour  does  not  exist  at  the  moment  the  tissue 
is  printed  on,  but  is  gradually  developed  on  the  fibre  as  the 
result  of  reactions  which  are  set  up  between  the  bodies  con- 
stituting the  mixture,  in  contact  with  atmospheric  oxygen 
at  a  certain  temperature.  It  consists  of  printing  on  the 
fabric  with  a  mixture  of — 


Chlorate  of  potash   25  grammes. 

Aniline   50  ,, 

Hydrochloric  acid  .....  50  ,, 

Bichloride  of.  copper  (of  i'44°)  .  50  ,, 

Sal  ammoniac   25  ,, 

Acetic  acid   12  ,, 

Starch  paste   1  litre. 


The  fabric,  after  having  been  printed  on  and  dried,  is 
exposed  to  the  air  in  oxidising  chambers  for  about  two  days. 
After  this  time  it  is  washed  in  feebly  alkaline  water,  and 
the  black  which  has  become  developed  in  the  oxidation 
chamber  will  be  fixed.  The  acid  of  the  aniline  salt  de- 
termines the  decomposition  of  the  chlorate  of  potash,  and 
at  the  same  time  the  bichloride  of  copper  reacts  on  the 
aniline.  The  result  of  this  readtion  is  the  production  of 
aniline  black,  which  is  quite  insoluble,  and  remains  fixed  on 
the  tissue. 

The  new  colour  was  at  first  received  favourably,  and  was 
immediately  adopted  in  Switzerland,  Germany,  England,  and 
France,  but  it  was  soon  almost  entirely  given  up,  owing  to 
grave  faults  which  attended  its  practical  employment  when 
prepared  in  this  manner.  The  large  quantity  of  bichloride 
of  copper  which  it  contains  causes  it  to  corrode  the  steel  or 
iron  cylinders  used  in  calico  printing,  and  impairs  the 
strength  of  the  fibre.  Moreover,  its  great  acidity  prevents  it 
being  kept  long  at  the  ordinary  temperature  without  decom- 
posing. The  reaction  then  takes  place  before  the  printing 
operation,  and  the  black  cannot  be  fixed. 


I40  REPORT  ON  THE  COAL  TAR  COLOURS 

Many  manufacturers  and  chemists  have  tried  to  modify 
the  formula  of  the  inventor,  and  overcome  the  difficulties  of 
its  employment.  Each  printer  added  something  to  the  mix- 
ture prescribed  by  Mr.  Lightfoot,  working  by  a  process 
which  was  perfeft  in  his  own  eyes,  and  which  he  took  great 
care  to  keep  as  secret  as  possible.  It  was  not  until  January, 
1865,  that  M.  Lauth  succeeded  in  remedying  the  principal 
inconveniencies  which  attended  the  production  of  aniline 
black  produced  by  Mr.  Lightfoot's  process,  by  simply  substi- 
tuting sulphide  for  bi-chloride  of  copper.  This  sulphide  is 
changed  into  sulphate  by  the  oxidising  aCtion  of  the  chloric 
acid,  the  chlorine,  or  one  of  the  chloro-derivatives  produced 
by  the  aCtion  of  chlorate  of  potash  on  hydrochlorate  of  aniline. 
The  conditions  then  become  similar  to  those  in  Lightfoot's 
process,  with  this  difference,  that  the  soluble  salt  of  copper 
does  not  exist  in  the  mixture  before  it  is  impressed  on  the 
fabric.  It  is  then  formed  gradually  and  simultaneously  with 
the  aniline  black,  and  is  decomposed  at  the  same  time,  con- 
sequently, there  is  no  corrosion  of  the  machinery  or  cylinders, 
and  no  particular  deterioration  in  the  strength  of  the  fibre. 
To  these  advantages  must  be  added  the  fadt  that  the  colour 
prepared  with  sulphide  of  copper  will  last  a  long  time,  and 
that  it  is  of  an  easy  oxidation.  Thanks  to  this  improvement, 
aniline  black  is  now  used  on  a  large  scale,  and  although  its 
employment  demands  a  certain  amount  of  skill  so  as  to  avoid 
injuring  the  fabric,  it  has  come  into  general  use. 

The  following  are  the  proportions  ordinarily  employed ; 
heat  and  digest  together : — 

Water  500  grammes. 

Starch  1000  ,, 

Sulphide  of  copper    .    .    .  250 

Afterwards  prepare  the  following  mixture  by  the  aid  of 
heat  :— 

Water   1850  grammes. 

Torrified  starch     ....  1200  ,, 
Solution  of  gum  tragacanth       1  litre. 
Hydrochlorate  of  aniline     .    800  grammes. 
Chloride  of  ammonium  .    .    100  ,, 
Chlorate  of  potash     .    .    .    300  ,, 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  141 

These  are  allowed  to  cool  and  then  mixed  together ;  they 
are  applied  in  the  usual  manner.  The  black  is  developed  in 
the  oxidation  chambers  at  a  temperature  of  between  200  and 
300,  under  the  double  influence  of  the  oxidising  agents  em- 
ployed, and  the  atmospheric  oxygen.  At  the  end  of  24  hours 
the  fabric  is  washed. 

The  nature  of  the  aniline  salt  which  forms  part  of  the  mix- 
ture is  a  matter  of  some  importance  ;  neither  the  acetate  nor 
the  citrate  of  aniline  can  be  employed  to  give  the  black,  and 
hitherto  printers  have  only  employed  successfully  the  hydro- 
chlorate  or  the  nitrate.  The  more  acid  the  aniline  salt  is, 
the  more  intense  is  the  black,  and  the  more  rapid  its  develop- 
ment. Unfortunately  the  ill  effects  of  too  great  acidity  of 
the  colouring  material,  in  respeCt  to  deterioration  of  fibre, 
and  corrosion  of  the  metallic  apparatus  employed,  render  it 
necessary  to  use  the  aniline  salts  as  neutral  as  possible. 

By  varying  the  process  which  gives  aniline  black,  other 
shades  which  approach  it,  more  or  less,  have  already  been 
obtained.  Thus,  with  the  following  receipt,  M.  Sacc  has 
obtained  brown  and  olive  tones  of  great  body — 

Water    ....  300  grammes. 
Flour      ....    36  „ 
Chlorate  of  potash  15 
Acetate  of  copper      15  „ 
Nitric  acid  ...    10  „ 
Aniline    ....    20  „ 

Aniline  black  may  be  employed  as  a  more  solid  basis  for 
composite  colours  than  logwood  or  iron,  and  thus  admits  of 
the  production  of  avast  number  of  shades.  It  perfectly  sup- 
ports dyeing  with  garancine,  and  all  the  operations  employed 
to  produce  red  and  garancine  rose  colours.  It  is  unalterable 
in  the  strongest  acid  or  alkaline  baths  ;  it  resists  most  oxi- 
dising agents,  and  all  temperatures  employed  in  steam  and 
oxidation  chambers,  and  it  may  therefore  be  associated  with 
all  metallic  steamed  colours.  The  adtion  of  steam,  however, 
gives  the  black  a  slight  green  tinge. 

In  short,  it  may  be  said  that  aniline  black  is  very  superior 
to  all  the  other  blacks  employed  in  dyeing,  and  it  would  be 
an  immense  boon  to  industry  if  means  were  discovered  to 


142 


REPORT  ON  THE  COAL  TAR  COLOURS 


render  it  applicable  to  printing  on  cloth;  hitherto  it  has 
shown  but  slight  affinity  for  wool.  On  the  other  hand,  it 
fixes  itself  perfectly  without  mordants  on  vegetable  fibres. 

No  solvent  is  known  which  is  capable  of  removing  aniline 
black  when  once  fixed  on  a  fabric  ;  it  may  be  said  to  be  com- 
pletely indelible. 

In  the  month  of  August,  1865,  M.  Paraf  proposed  a  mix- 
ture of  hydrochlorate  of  aniline,  chlorate  of  potash,  and 
hydrofluosilicic  acid  as  giving  a  very  beautiful  black,  and  not 
weakening  the  tissues.  Some  time  after  M.  Rosenstiehl 
pointed  out  that  a  mixture  of  chlorate  of  ammonia  and  hydro- 
chlorate  of  aniline  would  give  a  very  fine  black.  These 
receipts  indeed  produce  a  very  good  colour,  but  on  condition 
of  their  being  applied  with  a  copper  or  bronze  cylinder;  when 
the  above-named  mixtures  are  printed  with  a  plate  or  cylin- 
der of  wood,  so  arranged  as  to  absolutely  avoid  the  presence 
of  copper,  nothing  is  obtained  beyond  a  dirty  blue.  But  if 
to  this  mixture,  which  only  gives  a  blueish  grey,  increasing 
quantities  of  copper  are  added,  from  1  milligramme  up  to 
i"5  grammes,  the  grey  darkens  more  and  more,  until  finally 
a  very  fine  black  is  obtained.  It  appears  from  this  experi- 
ment, which  is  due  to  MM.  Lauth  and  Rosenstiehl,  that 
copper  is  an  essential  element  of  aniline  black. 

M.  C.  Koechlin,  who  has  worked  a  great  deal  on  aniline 
black,  is  not  of  this  opinion.  He  believes  that  copper  is  not 
one  of  the  necessary  constituents  of  aniline  black.  He  thinks 
that  the  copper  which  is  always  obtained  by  the  incineration 
of  a  tissue  printed  with  aniline  black  is  there  present  simply 
in  the  state  of  mixture,  and  that  it  can  be  completely  removed, 
without  altering  the  black  colour,  by  thoroughly  washing  the 
fabric  in  acid  liquids. 

According  to  this  chemist  a  black  is  prepared,  identical 
with  that  produced  on  fabrics,  by  boiling  together  the  follow- 
lowing  mixture  : — 

Aniline  .......  100  grammes. 

Hydrochloric  acid  .  .  .  100  ,, 
Ferrocyanide  of  potassium  50  ,, 
Chlorate  of  potash    ...      50  ,, 

Water   4000  ,, 


SHOWN  AT    THE    FRENCH    EXHIBITION,   1867,  I43 

After  three  or  four  days'  maceration  (the  author  does  not 
say  whether  hot  or  cold),  it  must  be  filtered  to  collect  the 
residue,  washed  in  water,  exhausted  by  alcohol,  then  treated 
with  an  acid,  and  finally  by  slightly  ammoniacal  water. 

It  has  never  been  demonstrated  that  the  substance  so  ob- 
tained is  quite  identical  with  the  black  produced  on  tissues 
by  the  aid  of  a  copper  salt,  neither  has  it  been  shown  that 
aniline  black  is  a  single  compound.  On  the  contrary,  ac- 
cording to  M.  E.  Kopp,  it  is  a  mixture  of  several  colouring 
matters,  of  emeraldine,  azurine,  and  all  the  colours  which 
are  produced  upon  oxidising  a  mixture  of  aniline  and  tolui- 
dine.  But  this  opinion  is  not  very  probable,  and  the  objec- 
tion may  be  raised  against  it  that  it  is  unlikely  for  a  mixture, 
as  in  this  case,  to  possess  none  of  the  chemical  properties  of 
its  constituents.  The  solvents  of  the  red,  violet,  blue,  green, 
and  yellow  dyes  do  not  dissolve  the  black,  and  its  affinities 
for  vegetable  or  animal  fibres  is  the  reverse  of  those  possessed 
by  the  colours  just  enumerated. 

To  sum  up,  the  chemical  history  of  this  black  is  yet  to  be 
ascertained,  and  all  that  is  known  of  it  is  a  few  of  its  pro- 
perties. It  is  completely  insoluble  in  hot  water,  alcohol, 
ether,  benzol,  boiling  soap,  alkalies,  and  acids  ;  it  is  slightly 
soluble  in  salts  of  aniline  ;  it  is  of  a  very  rich  velvety  black ; 
acids  change  it  to  green,  but  alkalies  bring  it  back  to  its  ori- 
ginal shade.  Dilute  bichromate  of  potash  increases  its  in- 
tensity, but  when  concentrated,  reddens  it.  Chlorine  and 
alkaline  hypochlorites  destroy  its  colour  after  some  time;  but, 
according  to  M.  C.  Kcechlin,  when  the  aftion  of  chloride  of 
lime  on  aniline  black  has  not  been  sufficiently  prolonged  for 
its  tint  to  be  completely  destroyed,  but  only  to  have  been 
brought  to  a  garnet  red,  a  very  curious  phenomenon  is  ob- 
served. The  original  black  colour  gradually  reappears,  until 
finally  it  becomes  of  the  same  intensity  which  it  was  before 
the  aftion  of  the  chloride  of  lime. 


144      -  *        REPORT  ON  THE  COAL  TAR  COLOURS 
DERIVATIVES  OF  PHENOL. 

I.   Phenic  or  Carbolic  Acid. 

Carbolic  acid,  discovered  by  Runge*  more  than  40  years  ago 
in  oil  of  coal  tar,  and  since  specially  examined  by  Laurent,! 
has  only  been  prepared  commercially  since  1840,  when  the 
latter  chemist  published  the  results  of  his  important  re- 
search. Indeed  almost  the  whole  of  the  creosote  at  this  time 
met  with  in  commerce  was  more  or  less  pure  carbolic  acid, 
and  was  produced  almost  entirely  in  Germany,  principally 
at  the  chemical  works  of  M.  E.  Sell,  of  Offenbach.  It  is  how- 
ever, to  Dr.  Crace  Calvert,  of  Manchester,  to  whom  belongs 
the  merit  of  having  first  prepared  this  body  in  the  crystalline 
form,  and  of  having  in  this  manner  greatly  contributed  to 
facilitate  and  extend  the  numerous  applications  of  which 
carbolic  acid  is  susceptible. 

The  improvements  effected  in  the  manufacture  of  aniline 
dyes  could  not  fail  to  influence  the  production  of  carbolic 
acid,  the  oils  which  contain  it  in  largest  quantity  being,  as 
it  were,  secondary  products  after  the  extraction  of  the  hydro- 
carbons required  in  the  aniline  industry. 

The  preparation  of  crystallised  carbolic  acid  is  a  matter  of 
no  difficulty,  if  care  is  taken  in  the  distillation  of  the  crude  acid 
to  collect  separately  that  which  passes  over  between  1600  and 
1900.  This  is  treated  with  caustic  soda,  and  the  carbolate 
of  soda  is  then  decomposed  by  sulphuric  acid  ;  the  oil  ob- 
tained in  this  manner  only  contains  very  little  cresylic  acid 
and  naphthalin.  By  successive  rectifications  a  product  is 
obtained  boiling  at  1800,  and  crystallising  easily  on  cooling. 

Owing  to  the  large  scale  on  which  this  body  is  produced, 
exceeding,  we  are  assured,  12  tons  a  week,  the  price  of  car- 
bolic acid  has  been  enormously  reduced  ;  besides,  the  value  of 
the  product  varies  with  its  point  of  fusion.  Carbolic  acid 
fusing  at  150  costs  if.  80c.  the  kilo.;  that  fusing  at  340  is 
worth  2  f.  20  c.  the  kilo. ;  whilst  that  which  does  not  fuse 
before  410  fetches  as  much  as  iof.  the  kilo. 

*  Runge,  Ann.  de  Poggend,  1834,  vol.  xxxi.,  p.  69  ;  xxxii.,  p.  308. 
f  A.  Laurent,  Ann.  de  Chim.  et  de  Phys.,  3rd  series,  vol.  iii.,  p.  95. 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  ;'"v\^45 

Amongst  the  numerous  applications  of  carboli'cs<aci45<^myv 
that  which  relates  to  the  manufacture  of  colouring^rttatters, 
interests  us  here.    We  will  point  out,  however,'  some „6f  its 
other  applications. 

In  the  crude  state,  it  is  used  for  the  preservation  of  wood 
employed  in  the  construction  of  railway  sleepers  and  in  ship 
building.  In  a  greater  state  of  purity  carbolic  acid  is  employed 
to  prevent  and  arrest  the  decomposition  of  easily  putrefactive 
animal  and  vegetable  substances.  It  serves  in  the  injec- 
tion of  corpses,  the  preservation  of  skins,  bones,  the  different 
stages  of  the  manufacture  of  parchment,  catgut,  glue,  gela- 
tine, and  lastly,  for  rendering  down  fatty  matters.  It  is  also 
advantageously  used  to  preserve  paste  and  starch,  and  it  is 
of  great  importance  in  the  disinfection  of  sewage,  tan  refuse, 
the  waters  in  which  hemp  and  flax  are  steeped,  the  waste 
liquids  of  refineries,  starch  works,  and  distilleries.  Finally, 
this  acid  is  applied  with  equal  success  to  the  purification  of 
hospital  wards  and  dissecting  rooms,  the  holds  of  ships, 
stables,  mews,  slaughter-houses,  privies,  &c. 

But  the  largest  quantity — about  half  the  production — is 
consumed  in  an  almost  pure  state  for  the  manufacture  of 
picric  acid  and  of  peonine  or  coralline. 

II.  Picric  Acid. 

The  purity  and  low  price  of  commercial  crystallised  car- 
bolic acid  at  the  present  day,  have  had  a  great  influence  on 
the  manufacture  of  picric  acid.  Hardly  six  years  ago  most 
manufacturers  found  it  advantageous  to  prepare  picric  acid 
by  treating  the  crude  oil  of  coal  tar,  or  the  resin  of  the 
xanthorrhea  hastilis,  with  nitric  acid.  Now  it  is  entirely  pre- 
pared from  crystallised  carbolic  acid. 

The  advantages  gained  by  the  employment  of  pure  crys- 
tallised carbolic  acid,  are  not  only  comprised  in  the  facility 
with  which  the  operation  proceeds,  and  in  the  economy  of 
nitric  acid,  the  greater  part  of  which  was  formerly  used  up 
in  attacking  the  impurities,  but  especially  in  the  facility 
with  which  the  picric  acid  is  purified.  All  the  foreign  sub- 
stances which  are  produced  when  the  xanthorrhea  hastilis 
resin,  or  crude  coal  tar  is  treated  with  nitric  acid,  are 


146 


REPORT  ON  THE  COAL  TAR  COLOURS 


entirely  absent ;  and  the  yield  of  picric  acid,  when  pure 
carbolic  acid  is  used,  is  almost  the  theoretical  quantity. 

The  preparation  of  this  substance  is  effected  by  carefully 
introducing,  in  small  quantities  at  a  time,  a  stream  of  nitric 
acid  into  pure  carbolic  acid,  or  into  a  previously  formed 
mixture  of  carbolic  and  sulphuric  acids  ;  or,  better  still, 
by  attacking  crystallised  sulphocarbolate  of  soda  by  nitric  acid. 

The  picric  acid,  as  met  with  in  commerce,  is  often  mixed 
with  foreign  substances,  such  as  sulphate  of  soda,  borax, 
oxalic  acid,  &c.  To  deteft  this  adulteration,  it  has  been 
suggested  to  treat  the  produft  with  benzol,  which  easily 
dissolves  the  picric  acid,  while  most  of  the  foreign  bodies 
remain  insoluble. 

The  best  proof  of  the  improvements  effected  in  the  manu- 
facture of  picric  acid  is  the  reduction  of  its  price.  In  1862,  a 
kilogramme  cost  from  25  to  30  frs.;  to-day  it  is  only  worth  iofrs. 

ill.  Derivatives  of  Picric  Acid. 

Picric  acid  is  susceptible  of  certain  metamorphoses  which 
have  been  attempted  to  be  utilised,  to  supply  the  wants  of 
the  tinctorial  industry. 

Isopurpuric  Acid. — Under  the  influence  of  cyanide  of 
potassium,  picric  acid  changes  to  a  red  coloured  acid,  the 
ammonia  salt  of  which  has  the  same  composition  as 
murexid.  It  has  been  named  isopurpuric  acid.  At  one  time 
this  compound  was  thought  to  be  identical  with  murexid, 
but  more  recent  researches  have  proved  that  the  two  bodies 
are  only  isomeric. 

The  preparation  of  isopurpurates  was  mentioned  in  the 
Reports  of  the  Universal  Exhibition  of  1862.  We  shall 
therefore  confine  ourselves  to  the  illustration  of  certain  im- 
provements which  have  been  illustrated  in  the  Exhibition  of 
1867.  According  to  a  communication  of  Dr.  C.  A.  Martius, 
Messrs.  Roberts,  Dale,  and  Co.,  of  Manchester,  had  already 
commenced  the  preparation  of  large  quantities  of  this  sub- 
stance some  years  ago.  Many  specimens  were  sent  at  the 
time  to  the  principal  dyers  of  Glasgow  for  trial.  But  the 
shades  furnished  by  this  body  were  not  then  the  fashion, 
and  their  introduction  was  limited.  New  experiments  appear 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  I47 

to  have  been  attended  with  a  better  result,  especially  in  the 
dyeing  of  wool  and  leather  •  we  may  state  that  the  samples 
of  merinos  exhibited  by  M.  Casthelaz,  dyed  with,  his  soluble 
ruby  (isopurpurate),  presented  very  fine  and  rich  tints. 

The  facility  with  which  the  isopurpurates  detonate  with 
the  least  shock,  renders  it  necessary  to  supply  these  pro- 
ducts in  the  form  of  paste,  containing  a  certain  quantity  of 
water.  During  the  first  essays  made  by  Messrs.  Roberts, 
Dale,  and  Co.,  a  terrible  explosion  took  place  in  their  labora- 
tory during  the  powdering  of  4  or  5  kilos,  of  isopurpurate  of 
potash,  the  violence  of  the  explosion  was  such  as  to  smash  all 
the  apparatus  in  the  laboratory,  and  the  workman  who  was  per- 
forming the  operation  was  hurled  to  the  ground.  Even  the  paste 
does  not  present  all  the  guarantees  of  security,  for  drying  re- 
stores its  explosive  properties.  To  remedy  this  serious  in- 
convenience, Dr.  Martius  suggests  the  addition  of  a  small 
quantity  of  glycerin,  which  keeps  the  substance  always  wet. 

The  low  price  of  picric  acid  allows  this  product  to  be  sold 
in  paste  (with  50  per  cent  of  water),  at  11  or  12  frs.  the 
kilo.  We  feel  justified  in  anticipating  soon  a  considerable 
demand  for  this  colouring  matter  ;  the  tendency  of  dyers,  in 
fadt,  is  more  and  more  to  replace  extracts  of  plants  and 
dyewoods  by  chemical  compounds  of  a  perfeft  purity ;  as 
these  have  a  constant  composition,  they  always  yield  the 
same  colours  under  the  same  conditions. 

Picramic  Acid. — Picramic  acid  is  also  a  derivative  of 
picric  acid ;  it  is  produced  when  the  latter  is  submitted  to 
the  reducing  aCtion  of  sulphide  of  ammonium.  Numerous 
attempts  have,  for  a  long  time,  been  made  to  apply  picramic 
acid  to  dyeing  purposes ;  but,  although  this  colouring  matter 
possesses  a  good  tinctorial  power,  and  resists  the  destructive 
aftion  of  light  very  well,  it  has  not  yet  taken  a  place  in 
commerce. 

*  IV.  Rosolic  Acid. 

This  name,  given  formerly  by  Runge  to  a  red  colouring 
matter  existing  in  oil  of  coal  tar,  is  used  now  to  designate  a 
tinftorial  substance  formed  by  the  aCtion  of  sulphuric  or 
oxalic  acids  on  carbolic  acid.  It  is  generally  admitted  that 
this  substance  is  the  same  as  that  obtained  by  Runge. 

l  2 


148 


REPORT  ON  THE  COAL  TAR  COLOURS 


The  first  publication  on  the  subject  of  this  produft  was 
made  by  MM.  Kolbe  and  Schmitt,  in  1861,*  who  prepared 
it  by  heating  a  mixture  of  1  part  of  oxalic  acid,  parts  of 
creosote,  and  2  parts  of  concentrated  sulphuric  acid.  In  a 
note  addressed  to  the  jury  of  Class  XLIV.,  M.  J.  Persoz  drew 
attention  to  the  fadt  that  the  formation  of  rosolic  acid,  by 
the  aCtion  of  sulphuric  and  oxalic  acids  on  carbolic  acid,  was 
observed  by  him  in  1859,  and  that  MM.  Guinon,  Marnas, 
and  Bonnet,  of  Lyon,  have  carried  out  commercially,  since 
i860,  the  process  with  which  he  furnished  them. 

Coralline  and  Azuline. — Rosolic  acid  submitted  to  the 
aftion  of  ammonia  under  pressure,  at  a  temperature  of  1500, 
is  changed  into  a  red  colouring  matter,  called  peonine 
(coralline).  This  body,  heated  to  1800  in  the  presence  of 
aniline,  gives  rise  to  a  blue  colouring  matter,  called  azuline. 
The  discovery  of  these  two  colours  is  due  to  M.  Jules  Persoz, 
and  patents  for  their  preparation  were  taken  out  in  1862  by 
MM.  Guinon,  Marnas,  and  Bonnet. 

The  details  of  the  manufacture,  as  given  by  the  patent, 
having  been  published  in  the  1862  Exhibition  report,  we 
shall  not  give  them  here  ;  but  will  only  add,  that  experience 
has  shown  that  to  obtain  the  finest  shades  and  best  yield, 
there  must  be  used  carbolic  acid,  boiling  at  a  constant  tem- 
perature of  1840,  and  perfectly  dry  oxalic  acid. 

The  rosolic  acid  which  is  met  with  in  commerce,  is  in  the 
form  of  a  brittle  resin  of  a  cantharides  lustre,  or  in  fine 
powder  of  a  brownish  red  colour. 

Experiments  made  with  the  view  of  applying  pure  rosolic 
acid  to  tinctorial  purposes,  have  not  been  crowned  with 
success.  Of  the  two  colouring  products  derived  from  rosolic 
acid,  only  peonine  (coralline)  has  acquired  a  certain  com- 
mercial importance.  Its  principal  uses  are  in  silk  dyeing, 
calico  printing,  and  the  production  of  lakes  employed  in 
the  manufacture  of  tinted  papers  and  lithographic  colours. 

The  blue  colouring  matter  formed  by  the  aCtion  of  aniline 
on  peonine  is  no  longer  made,  being  replaced  in  commerce 
by  aniline  blue. 

*  Kolbe  and  Schmitt,  Ann.  der  Chem.  u.  Pharm.,  lxix.  169. 


SHOWN  AT  THE  FRENCH   EXHIBITION,  1867.  T49 


DERIVATIVES  OF  NAPHTHALIN. 

h  Naphthylamine  Yellow. 

Amongst  the  numerous  processes  which  have  been  pointed 
out  for  the  transformation  of  naphthalin  into  colouring  sub- 
tances,  only  one  has  been  commercially  applied.  This 
process,  which  we  owe  to  Dr.  C.  A.  Martius,  enables  us  to 
obtain  a  magnificent  yellow  colouring  matter,  which,  in 
France  goes  under  the  name  of  jaune  d'or,  and  in  England, 
of  Manchester  yellow. 

Naphthalin  is  obtained  in  the  distillation  of  coal;  it  is 
principally  found  in  the  heavy  oils  which  remain  after  the 
separation  of  the  hydrocarbons  which  yield  benzol,  toluol, 
and  the  phenols. 

The  quantity  of  naphthalin  produced  in  the  distillation  of 
coal  appears  to  vary  according  to  its  nature,  and  the  plan 
of  carbonisation  followed.  It  forms  a  residue  in  gasworks, 
especially  in  those  where  tar  is  manufactured  either  for  the 
preparation  of  hydrocarbons,  or  for  the  manufacture  of 
artificial  fuel. 

When  treated  by  similar  processes  to  those  already  de- 
scribed for  the  transformation  of  benzol  into  nitro-benzol 
and  aniline,  naphthalin  furnishes  nitronaphthalin  and  naph- 
thylamine, a  base  analogous  to  aniline,  and  which  forms 
the  starting  point  for  the  production  of  Manchester  yellow. 
To  prepare  this,  a  neutral  solution  of  hydrochlorate  of 
naphthylamine  is  added  to  nitrite  of  soda,  until  all  the 
naphthylamine  is  transformed  into  diazonaphthol.  The 
liquid  which  contains  the  hydrochlorate  of  diazonaphthol  is 
mixed  with  nitric  acid,  and  heated  to  ebullition.  The  yellow 
colouring  matter  separates  and  floats  on  the  surface  in  the 
form  of  small  yellow  needles,  which  are  collected  with  a 
large  skimmer.  To  purify  it,  it  is  dissolved  in  ammonia  and 
filtered. 

According  to  the  experiments  of  Dr.  Martius,  this  yellow 
compound  is  binitronaphthol,  which  stands  in  the  same 
relation  to  naphthalin  as  binitrophenol  does  to  benzol.  It 
is  an  acid  analogous  to  picric  acid,  and  forms  with  bases 


150  REPORT  ON  THE  COAL  TAR  COLOURS 

salts  which  are,  for  the  most  part,  well  crystallised,  and 
possess  a  more  or  less  orange  colour.  Binitronaphthylic 
acid  is  already  employed  extensively  in  dyeing  wool  and 
leather;  it  is  also  used  to  colour  many  other  substances, 
amongst  which  we  may  name  soap. 

This  colouring  body  is  remarkable  for  the  brilliant  golden 
yellow  shades  which  it  communicates  to  fabrics,  and  which 
are  easily  distinguishable  from  those  given  by  picric  acid,  the 
latter  yielding  much  greener  tints.  This  is  not  the  whole  ad- 
vantage which  it  possesses  over  picric  acid  ;  the  tints  which 
it  furnishes  admit  of  being  steamed,  whilst,  on  the  contrary, 
those  given  by  picric  acid  are  destroyed  by  this  operation. 

Hitherto  the  very  high  price  of  binitronaphthylic  acid  (50 
francs  the  kilo.)  has  prevented  its  general  adoption  as  a  dye. 
We  should,  however,  remark  that  for  equal  weights  its  tinc- 
torial power  is  much  greater  than  that  of  picric  acid. 

II.  Benzoic  and  Chloroxynaphthalic  Acids. 

Attempts  have  recently  been  made  to  utilise  naphthalin 
as  a  source  of  benzoic  acid,  a  substance  which,  as  already 
stated  (page  124),  is  often  employed  in  the  transformation 
of  rosaniline  into  the  blue  colouring  matter.  These  experi- 
ments are  the  more  interesting,  as  they  have  given  rise  to 
the  production  of  secondary  products  capable  of  being  applied 
to  dyeing  and  calico  printing.  Hitherto  benzoic  acid  has  been 
extracted  either  from  gum  benzoin,  or  from  the  hippuric  acid 
contained  in  the  urine  of  herbivorous  animals.  It  has  now 
been  proposed  to  prepare  it  by  decomposing  phthalic  acid,  a 
derivative  of  naphthalin  made  known  by  the  researches  of 
Laurent  and  M.  de  Marignac. 

The  composition  of  phthalic  and  benzoic  acids  presents  a 
very  simple  relation.  Benzoic  acid  contains  the  elements 
of  phthalic  acid,  minus  one  molecule  of  carbonic  acid.  Be- 
tween these  two  acids  there  is  the  same  difference  of  com- 
position as  between  benzoic  acid  and  benzol,  a  hydrocarbon 
which  can  be  produced  by  removing  one  molecule  of  carbonic 
acid  from  benzoic  acid. 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  151 

It  was  known  that  when  phthalic  acid  is  submitted  to  the 
aftion  of  lime  with  the  agency  of  heat  it  splits  up  into  benzol 
and  two  molecules  of  carbonic  acid.  It  was  therefore  probable 
(and  Gerhardt,  and  more  recently  Berthelot,  had  pointed  this 
out)  that  phthalic  acid  could  be  transformed  into  benzoic  acid 
by  arresting  the  aftion,  as  it  were,  half  way.  M.  Dusart* 
tried  to  effeft  this  decomposition ;  but  although,  on  distilling 
a  mixture  of  phthalate  and  oxalate  of  soda  with  lime,  he  suc- 
ceeded in  obtaining  a  small  quantity  of  oil  of  bitter  almonds, 
he  did  not  succeed  in  transforming  phthalic  acid  into  benzoic 
acid. 

This  reaction  has  been  since  effected  by  MM.  P.  and  E. 
Depouilly.t  They  took  one  molecule  of  bicalcic  phthalate, 
and  one  molecule  of  hydrate  of  lime,  and  heated  the  mixture 
for  several  hours  to  a  temperature  of  from  3300  to  3500 ;  the 
salt  is  then  entirely  converted  into  benzoate  and  carbonate 
of  lime.  The  benzoate  of  lime  is  dissolved  in  water,  the 
solution  concentrated,  and  the  benzoic  acid  precipitated  by 
an  acid.  Laurent  described  phthalic  acid  in  his  great  work 
on  the  derivatives  of  naphthalin,  published  in  1832  to  1845. 
He  obtained  it  by  oxidising  the  chlorine  substitution  products 
of  naphthalin  with  nitric  acid.  The  following  is  the  plan 
which  MM.  P.  and  E.  Depouilly  finally  adopted  : — Naph- 
thalin is  treated  in  the  cold  with  a  mixture  of  chlorate  of 
potash  and  hydrochloric  acid.  In  this  manner  by  one  opera- 
tion are  obtained  a  large  quantity  of  quadrichlorides  of  naph- 
thalin and  chloronaphthalin,  together  with  a  very  small 
quantity  of  subchlorides  ;  these  latter  are  removed  by  pres- 
sure. The  solid  residue,  which  is  a  mixture  of  quadrichloride 
of  naphthalin  and  of  quadrichloride  of  chrononaphthalin,  is 
attacked  by  nitric  acid  on  a  water  bath.  The  former  changes 
into  phthalic  acid,  and  the  latter  into  chloride  of  chloroxy- 
naphthyl,  which,  by  modifying  the  temperature,  also  gives 
phthalic  acid.  The  mixture  of  chlorate  of  chloroxynaphthyl 
and  of  phthalic  acid  is  extracted  with  boiling  water,  which 
only  removes  the  phthalic  acid. 

*  Comptes  Rendus  de  l'Academie,  1862,  lv.,  44. 
f  Comptes  Rendus  de  l'Academie,  lx.,  456. 


152  REPORT  ON  THE  COAL  TAR  COLOURS 

The  chlorate  of  chloroxynaphthyl  is  capable  of  yielding  a 
beautiful  crystalline  substance  of  a  very  brilliant  orange 
yellow  colour;  this  is  the  chloroxynaphthalic  acid  of  Laurent. 
To  obtain  this  acid  the  chloride  of  chloroxynaphthyl  is  treated 
with  an  alcoholic  solution  of  potash,  which  transforms  it  and 
dissolves  it  in  the  state  of  chloroxynaphthalate  of  potash. 

The  solution  is  decanted  or  filtered  from  the  residue,  and 
decomposed  by  a  mineral  acid.  Chloroxynaphthalic  acid 
deposits,  but  in  an  impure  state  ;  to  purify  it  it  is  transformed 
into  a  neutral  potash  salt.  This  is  treated  with  a  solution  of 
alum,  which  precipitates  a  brown  colouring  matter  differing 
from  chloroxynaphthalic  acid  in  colour.  The  filtered  liquid 
precipitated  by  a  mineral  acid  deposits  chloroxynaphthalic 
acid  in  the  form  of  a  crystalline  powder  of  a  pale  yellow 
colour,  which  colours  wool  an  intense  red  without  a  mordant. 
This  substance  is  very  beautiful,  and  will  probably  meet  with 
important  applications  in  dyeing  and  printing.  Unfortunately, 
the  process  by  which  it  is  obtained  is  very  long  and  costly, 
and  consequently  the  price  of  the  product  is  high. 

In  conclusion,  we  may  perhaps  be  permitted  to  direct  anew 
the  attention  of  manufacturers  to  chloroxynaphthalic  acid, 
which  is  perhaps  destined  to  play  an  important  part  in  the 
history  of  artificial  colouring  matters.  In  his  Traite  de 
Chimie  Organique,  Gerhardt*  pointed  out  the  very  simple 
relation  which  existed  between  the  composition  of  chloroxy- 
naphthalic acid  and  of  alizarin,  the  colouring  principle  of 
madder.  Indeed,  by  replacing  the  chlorine  in  chloroxynaph- 
thalic acid  with  an  equivalent  of  hydrogen,  we  obtain  the 
formula  of  alizarin.  t  All  experiments  which  have  hitherto 
been  tried  to  effedt  this  important  transformation  have  failed. 
Doubts  have  even  been  expressed  as  to  the  possibility  of  ever 
succeeding  in  it ;  at  the  same  time  all  hopes  of  seeing  this 
change  realised  ought  not  to  be  abandoned. 

*  Gerhardt,  Traite  de  Chimie  Organique,  iii.,  478. 
f  Chloroxynaphthalic  acid  €I0H5C1G3 
Alizarin  Gi0He  03 


SHOWN  AT  THE  FRENCH  EXHIBITION,  1867.  153 


OTHER  APPLICATIONS  OF   THE  COAL  TAR  COLOURING 

MATTERS. 

The  other  applications  of  these  colours  are  numerous,  and 
although  they  do  not  consume  so  large  quantities  as  are  used 
in  dyeing,  they  still  deserve  some  attention.  It  is  always 
interesting  to  follow  the  attempts  made  by  manufacturers  to 
adapt  to  the  most  varied  wants  every  new  substance  which 
enters  their  domain,  to  multiply  its  applications,  and  thus  to 
force  it  to  yield  up  the  sum  total  of  utility  which  it  virtually 
contains. 

Since  1862,  the  paper-maker  has  used  large  quantities  of 
aniline  colours  either  to  blue  his  pulp,  to  tint  it,  or  to  com- 
municate a  superficial  colour  to  paper  when  finished.  Their 
solubility  in  water  has  caused  their  use  rapidly  to  extend, 
and  now  they  have  almost  entirely  replaced  all  the  sub- 
stances which  were  formerly  employed,  such  as  ultramarine, 
different  metallic  oxides,  extracts  of  wood,  &c.  Of  all  the 
aniline  colours,  that  most  used  in  paper-making  is  the  soluble 
blue.  It  may  be  used  either  by  mixing  its  aqueous  solution 
diredt  with  the  paper  pulp,  or  when  it  is  sized. 

Many  objects  of  stationery  are  ornamented  by  means  of 
these  colours,  such  as  the  designs  in  imitation  of  porcelain. 
These  are  made  by  printing  a  design  on  a  sheet  of  ordinary 
paper  by  means  of  a  lake  of  aniline  dye  dissolved  in  a  salt  of 
aniline.  This  is  then  taken  off  on  to  a  sheet  of  paper  strongly 
albuminised  and  damped.  The  colour  is  fixed  with  albumen, 
and  a  pretty  looking  reproduction  of  the  original  design  is 
thus  obtained  with  rich  full  tints. 

Most  wafers,  powders  for  drying  ink  (sand,  pounce,  &c.,) 
are  coloured  with  aniline  dyes.  Certain  coloured  inks,  espe- 
cially the  red  and  violet  inks,  are  manufactured  from  salts 
of  rosaniline  and  methyl-rosaniline.  They  are  generally 
aqueous  solutions  containing  a  sufficient  quantity  of  gum  or 
dextrine,  and  containing  a  little  glycerin.  They  are  very 
rarely  formed  of  lakes  held  in  suspension. 

Inks  for  typography  are  also  made  with  these  substances. 
One  of  the  first  processes  employed  consists  in  dissolving 


154  REPORT  ON  THE  COAL  TAR  COLOURS 

the  colours  in  alcohol  containing  a  resin  in  solution,  and 
then  precipitating  the  whole  by  water.  The  dried  precipi- 
tate is  ground  up  with  a  suitable  quantity  of  varnish  and 
zinc  or  baryta  white.  Another  process  consists  in  mixing 
with  varnish,  starch  coloured  with  the  aniline  dye.  A  third 
is  to  precipitate  the  colouring  matter  with  an  alkali  so  as  to 
obtain  the  base ;  the  dried  precipitate  is  dissolved  in  oleic 
acid,  and  then  mixed  with  a  lithographic  varnish  free  from 
lead. 

The  aniline  dyes  are  also  utilised  in  the  manufacture  of 
lakes  to  be  used  in  staining  or  colouring  paper,  in  water 
colour  painting,  in  colouring  designs  and  especially  photo- 
graphs. For  this  latter  purpose  they  have  the  advantage  of 
being  perfectly  transparent,  of  allowing  the  most  minute 
details  to  be  seen,  and  of  forming  an  intimate  combination 
with  the  albuminised  paper  used  in  photography.  They  are 
prepared  by  taking  advantage  of  the  property  they  possess  of 
combining  with  certain  metallic  oxides  or  other  substances, 
such  as  kaolin,  starch,  tannin,  &c.  With  this  object,  a  soluble 
salt  of  the  colouring  substance  is  precipitated  by  a  solution  of 
a  metallic  salt,  the  oxide  of  which  forms  an  insoluble  com- 
pound with  the  acid  of  the  colour  salt ;  or  better  still,  by  pre- 
cipitating mixed  solutions  of  the  colouring  matter  and  metallic 
salt  by  ammonia  or  carbonate  of  soda.  The  best  lakes  are 
obtained  when  the  precipitation  of  salts  of  aniline  red,  violet, 
or  blue  is  effected  in  the  presence  of  benzoic  acid.  Starch, 
kaolin,  and  alumina,  added  to  solutions  of  these  dyes,  de- 
colourise them  rapidly,  absorbing  all  the  colour,  and  becom- 
ing tinted  in  the  same  manner  as  silk  or  woollen  fabrics. 
Tannin  precipitates  aniline  red  very  completely  from  its 
aqueous  solutions,  and  forms  with  it  an  insoluble  lake  of  a 
fine  carmine  colour  ;  sulphate  of  alumina  is  sometimes  mixed 
with  the  tannin.  The  following  is  the  plan  ordinarily 
adopted  : — Carbonate  of  soda  is  mixed  with  sulphate  of 
alumina  so  as  to  exactly  neutralise  the  liquid  without  precipi- 
tating it ;  the  solution  of  the  colouring  matter  is  then  added, 
and  the  whole  is  precipitated  with  tannin.  The  coloured 
powders  so  largely  employed  in  the  manufacture  of  flock 
paper  for  wall  decoration,  are  prepared  by  grinding  up  woollen 


SHOWN  AT  THE  FRENCH  EXHIBITION,   1867.  155 


shreds,  and  dyeing  them  in  various  tints  of  aniline  colours  by 
the  ordinary  processes.  Most  of  these  lakes,  mixed  with 
drying  oils  or  varnish,  may  also  be  used  in  the  preparation 
of  printing  inks. 

A  method  of  laquering  wood,  in  which  the  metallic  reflec- 
tion possessed  by  these  colours  in  the  solid  state  is  preserved, 
is  effected  by  immersing  the  wood  in  hot  concentrated  alco- 
holic solutions  of  the  aniline  dyes.  The  wood  is  rapidly 
dried  in  a  current  of  warm  air,  and  then  coated  with  a  trans- 
parent varnish  made  of  copal  dissolved  in  ether.  Owing  to 
its  insolubility  in  this  vehicle,  the  colouring  matter  preserves 
all  its  lustre,  and  is  protected  from  moisture  and  fridtion  by 
the  hard,  insoluble,  adherent  pellicle  which  the  varnish  leaves 
on  drying.  These  processes  have  lately  been  applied  to  the 
dyeing  and  coloration  of  straw  for  bonnets,  and  to  the  manu- 
facture of  artificial  leaves.  The  process  is  similar  to  that 
described  for  laquering  wood. 

The  aniline  dyes  are  equally  applicable  to  the  decoration 
of  glass  and  porcelain,  when  required  exclusively  for  orna- 
mental purposes.  They  are  applied  by  dissolving  in  alcohol, 
and  painting  on  with  a  brush,  and  are  afterwards  coated  with 
a  transparent  resinous  varnish  insoluble  in  water.  Objects 
so  decorated  look  like  enamels,  but  have  neither  their  quality 
nor  permanency.  In  this  list  of  secondary  applications,  one 
must  be  mentioned  which  employs  considerable  quantities  of 
these  colours  ;  this  is  the  decoration  of  glass  globes  used  for 
public  illuminations.  They  are  prepared  by  dipping  the 
globes  in  a  solution  of  albumen,  blood,  or  gelatin,  and  then 
removing  and  drying  them  ;  they  are  then  passed  through  a 
bath  of  the  dye.  In  this  way  globes  are  obtained  possessing 
the  same  lustre  as  glasses  coloured  with  cobalt  or  purple  of 
Cassius. 

Pearls  and  precious  stones  are  imitated  by  a  similar  pro- 
cess more  carefully  carried  out.  The  same  plan  is  adopted 
for  the  coloration  of  mother  of  pearl,  ivory,  bone,  and  other 
substances  of  animal  origin.  These,  however,  are  able,  par- 
tially, to  combine  direft  with  the  colouring  matter. 

The  art  of  perfumery  also  has  recourse  to  the  aniline 
dyes  for  the  coloration  of  essences,  soaps,  cold  cream, 


156  REPORT  ON  COAL  TAR  COLOURS,  1867. 

pomades,  rice-powder,  &c.  Their  application  to  these 
different  uses  is  self-evident ;  and,  granting  the  utility  (a 
very  questionable  one)  of  the  unguents  with  which  the 
fair  sex  love  to  anoint  themselves,  we  are  constrained 
to  admit  that  the  introduction  of  the  aniline  dyes  to 
this  branch  of  industry  has  been  of  undoubted  service. 
They  have  superseded  the  metallic  substances — the  prepara- 
tions of  mercury,  of  bismuth,  and  of  lead — which  were  almost 
all  injurious  to  health.  As,  however,  it  is  not  our  wish  to 
destroy  pleasant  illusions,  we  shall  not  enter  into  more  ample 
details  on  so  mysterious  a  subjedl. 

To  abridge  this  enumeration,  already  too  long,  of  the  trades 
employing  the  aniline  dyes,  we  will  content  ourselves  with 
mentioning  the  blueing  of  linen,  the  tinting  of  candles 
and  wax  vestas,  the  coloration  of  white  vinegar  to  imitate 
wine  vinegar,  and  lastly  the  fabrication  of  syrup  of  rasp- 
berries in  America. 

A  few  words  are  required  for  a  recent  scientific  application. 
Aniline  red,  blue,  and  violet,  dissolved  in  water  or  dilute 
alcohol,  are  daily  employed  by  microscopists  for  the  soaking 
of  tissues,  of  which  the  anatomical  elements  are  coloured 
unequally,  so  that  some  of  them  become  more  visible  under 
the  microscope.  Carmine  dissolved  in  ammonia  was  for- 
merly employed  for  this  purpose,  but  the  aniline  colours  are 
preferable  in  many  cases  where  the  delicacy  of  the  tissues 
would  be  unable  to  resist  the  aftion  of  ammonia. 

In  a  similar  manner  M.  C.  Legros  uses  the  red,  blue,  and 
violet  to  colour  collodion  with  which  he  injedts  the  vessels 
of  men  and  animals  for  anatomical  purposes.  This  injection 
is  very  penetrating,  and  permeates  the  most  delicate  capil- 
laries, whilst  at  the  same  time  the  colours  preserve  all  their 
brilliancy  without  injuring  the  transparency  of  the  tissues. 
Specimens  injedted  in  this  manner  may  be  preserved  very 
well  in  glycerin.  This  injection  may  be  employed  cold,  and 
admits  of  the  anatomical  specimens  being  dried  quickly. 


INDEX. 


INDEX. 


ACETATE  of  aniline,  21 
—  of  iron,  14 
Acetate  of  rosaniline,  48,  50,  118 
Acetyl  substitutes  of  rosaniline,  74 
Acid,  anthranilic,  13 

—  carbolic,  2,  144 

—  nitric,  8 

—  phenic,  2,  4,  12 

—  sulphuric,  8 
Aldehyd  green,  80,  81,  133 
Almonds,  bitter,  oil  of,  6 
Aldehyd,  preparation  of,  80 
Amide  of  phenyl,  13 
Ammonia,  12 

—  phenate  of,  12 
Ammoniacal  water,  2 

Anderson  and  Anders,  MM.,  disco- 
vered picoline,  naphthalin,  and 
paranaphthalin,  12 

Aniline,  12 

—  acetate  of,  21 

—  apparatus  for  manufacture  of,  on 

the  large  scale,  14 

—  Bechamp's  process  for  preparation 

of,  14,  no 

—  black,  84,  138 

— -  blue,  composition  of,  67 

 and  violet,  55,  123 

 manufacture  of,  on  the 

large  scale,  63 

—  brown,  92,  137 

— ■  colours,  decolourising  with  zinc,  94 
 determination     of  tinctorial 

power  and  intensity  of,  95 
 table  for  the  identification  of, 

98 

—  green,  77,  81 

—  Hofmann  and  Laurent's  method 

of  producing,  13 

—  hydriodate  of,  21 

—  hydrochlorate  of,  12,  17,  21 

—  maroon,  137 


Aniline,  nitrate  of,  21 

—  oil,   common,   test   for  colorific 

power  of,  26 

 properties  of  commercial,  19, 

25 

—  oxalate  of,  20 

—  poisonous  nature  of,  31 

—  red,  33 

—  scarlet,  91 

—  sulphate  of,  13,  ig,  20 

—  yellow,  89 
Antimony,  nitrate  of,  45 
Anthranilic  acid,  13 

Apparatus  for  the  lixivation  of  crude 

magenta,  43 
 manufacture  of  aniline  on  the 

large  scale,  14 
Applications  of  the  coal  tar  colours, 
126 

Argentine,  81 

Arseniate  of  rosaniline,  42 

Arsenic  acid  used  for  preparing 
magenta,  38 

 regeneration  of,  122 

Arsenious  acid  used  in  the  manufac- 
ture of  aniline,  17 

Asphalt,  3 

Azalein,  36,  47 

Azobenzol,  16 

Azuline,  148 

BARANILINE,  27 
Beale  and  Kirkham's  process 
for  preparing  aniline  violet,  57 
Bechamp's  process  for  preparation  of 

aniline,  14 
 preparing  aniline  blue,  56, 

58 

Benzidam,  14 
Benzoic  acid,  150 
Benzol,  1,  18 

—  distillation  of,  4 


i6o 


INDEX. 


Benzol,  distillation  of  by  means  of 

steam,  4 
Benzols,  . 

—  heavy,  4 

—  light,  3 

Bichloride  of  carbon,  34 

 tin,  35 

Binitrobenzol,  11 

Binitronaphthylic  acid,  150 

Binitronaphthol,  149 

Bitter  almond  oil,  6 

Black,  aniline,  84,  138 

 Cordillot's  process  for  pre- 
paring, 85 

 Hughes's  process  for  pre- 
paring, 87 

 Kappelin's  process  for  pre- 
paring, 87 

 Lightfoot's  process  for  pre- 
paring, 85,  139 

  Lauth's  process  for  preparing, 

86,  142 

Blackley's  process  for  preparing 
magenta,  38 

Bleu  de  Fay  bile ,  64 

 Luniiere,  64,  127 

 Lyons,  61 

  Mexique,  64 

 Mulhouse,  58 

 Nuit,  61,  64 

 Paris,  58 

Blue,  aniline,  55,  123 

 Bechamp's  process  for  pre- 
paring, 56,  58 

 Coleman's  process  for  pre- 
paring, 58 

 composition  of,  67 

 from  diphenylamine,  75 

 Fritsche's  process  for  pre- 
paring, 56 

 Gilbee's  process  for  preparing 

61 

 Girard  and  de  Laire's  pro- 
cess for  preparing,  59 

 Hofmann's  process  for  pre- 
paring, 56 

 Holliday's  process  for  pre- 
paring, 62 

 Koechlin's  process  for  pre- 
paring, 56 

 Kopp's  process  for  preparing,  59 

 Lauth's  process  for  preparing, 

 Passavant's  process  for  pre- 
paring, 61 

 Persoz,  de  Luynes,  and  Sal- 

vetat's  process  for  preparing, 

58 

 Price's  process  for  preparing, 

60 

 Schaffer     and  Gros-Rey- 

nard's  process  for  preparing,  58 


Blue,  aniline,  Schlumberger's  pro- 
cess for  preparing,  61 

 Williams's  process  for  pre- 
paring, 58,  63 

 and  violet,  manufacture  of,  on 

a  large  scale,  63 

—  mauveine,  137 
Boghead  coal,  tar  of,  4 

Bolley's  process  for  preparing 
aniline  blue,  60 

Brominated  oil  of  turpentine,  76 

Brooman's  process  for  preparing 
magenta,  35 

Brown,  aniline,  92,  137 

 de  Laire's  process  for  pre- 
paring, 92 

 Kcechlin's  process  for  pre- 
paring, 93 

—  from  leukaniline,  93 


CANNEL  coal,  tar  of,  4 
Carbolic  acid,  2,  144 

■  uses  of,  145 

Carbon,  bichloride  of,  34 
Carbonate  of  mauveine,  69 
Chinoline,  properties  of,  23 

—  sulphate  of,  24 
Chloroxynaphthylic  acid,  150 
Chloroxynaphthyl,  151 
Chromate  of  rosaniline,  51 
Chrysaniline,  53,  90,  120 

—  hydrochlorate  of,  53 

—  nitrate  of,  54 

—  sulphate  of,  54 
Chrysotoluidine,  121 

Coal,  Boghead,  Cannel,  Newcastle, 
and  Staffordshire,  tar  of,  4 

—  gas,  2 

—  tar,  2 

Coleman's    process    for  preparing 

aniline  blue,  58 
Colorific  power  of  common  aniline 

oil,  26 

Colours,  aniline,  determination  of 
tinctorial  power  and  intensity 
of,  95 

Coralline,  148 

Cordillot's  process  for  preparing 

aniline  black,  85 
Creosote,  2 

Crossley's    process   for  preparing 

aniline  purple  and  yellow,  57 
Cumidine,  19 
Cumol,  2,  4,  18 
Cumyl,  18 

—  hydrogen  compound  of,  2,  6 
Cyanol,  12 

Cymidine,  19 
Cymol,  2,  4,  18 
Cymyl,  18 

—  hydrogen  compound  of,  2,  6 


DAHLIA,  64 
Dale  and  Caro's  process  for 
preparing  aniline  violet,  58 
 process  for  preparing  ma- 
genta, 37 
Decolourising  aniline  colours,  94 
De   Laire's   process   for  preparing 

aniline  brown,  92 
Delvaux's    process    for  preparing 

magenta,  47 
Depouilly  and  Lauth's  process  for 

preparing  magenta,  38 
Diamond  magenta,  44 
Diazonaphthol,  149 
Diphenylamine,  75,  in 
Diphenylrosaniline,  68 
Distillation  of  benzol,  4 

 by  means  of  steam,  4 

 naphthalin,  5 

Ditolylamine,  in 
Dry  tar,  4 

EMERALDINE,  76,  81 
Ethyl,  iodide  of,  preparation  of, 
73 

Ethylaniline,  74 

Ethylation,  violet  produced  by,  129 
Ethylphenylamine,  74 
Ethylrosaniline,  74,  131 
Essence  of  Mirbane,  6,  7 

FOL'S  process  for  preparing  ma- 
genta, 46 
Formiate  of  rosaniline,  51 
Fritsche's    process   for  preparing 

aniline  blue,  56 
Fritsche,    M.,    produced  aniline 

from  indigo,  13 
Fuchsiacine,  34 
Fuchsine,  34,  47 
Furfurol,  46 

GEBER-KELLER'S  process  for 
preparing  magenta,  36 
'  Gilbee's  process  for  preparing  ani- 
line blue  and  violet,  61 
Girard  and  de  Laire's  process  for 
preparing  aniline  blue  and  violet, 
59 

 magenta,  39 

Gratrix's  process  for  the  prepara- 
tion of  magenta,  45 
Green,  aniline,  77,  133 

 from  aldehyd,  80,  81,  133 

 iodide  of  ethyl,  133 

 Lucius's  process  for  preparing, 

81 

 Usebe's  process  for  preparing, 

82 

 Wilm's  process  for  preparing, 

76 

Grey  from  mauveine,  137 


><v   <^  '  -V/ 

HA  VAN  IK  A  >r^^ , v  92 
Heavy  bejteols,  a   o  y/ 

—  hydrocarbons,  2  \^  \  V^j£i*<*r 
Hofmann's    pftfce«SH«-ftjr  preparing 

aniline  blue,  56,  62 
 magenta,  34 

—  researches  on  aniline  blue  and 

violet,  66 
 on  magenta,  48 

—  violet,  70 

Hofmann  and  Laurent's  method  of 

producing  aniline,  13 
Hughes's  process  for  preparing  ani- 
line black,  87 

 magenta,  38 

Huile  de  Mirbane,  6,  7 
Hydrate  of  oxide  of  phenyl,  2 
Hydrocarbons,  light  and  heavy,  2 
Hydriodate  of  aniline,  21 

 ethyl-  and  methyl-rosaniline,  131 

Hydrobromate  of  rosaniline,  50 
Hydrochlorate  of  aniline,  12,  17,  21, 
116 

—  of  chrysaniline,  53 

—  of  leukaniline,  51 

—  of  mauveine,  69 

—  of  toluidine,  22 

—  of  triphenyl-rosaniline,  67 
Hydrochlorates  of  rosaniline,  49 
Hydrogen,  naphthylated,  3 

—  phenylated,  1 

INDIGO,  aniline  produced  by  heat- 
ing, 13 

Intensity  of  aniline  colours,  determi- 
nation of,  95 

Iodide  of  methyl  or  ethyl,  preparation 
of>73 

 ethyl  green,  133 

Iron,  acetate  of,  14 
Isatate  of  potash,  13 
Isopurpuric  acid,  146 

KAPPELIN'S  process  for  prepar- 
ing aniline  black,  85 
Kcechlin's    process    for  preparing 
aniline  blue,  56 

 printing  in  aniline  black,  85 

 preparing  aniline  brown,  93 

 magenta,  46 

Kopp's  process  for  preparing  aniline 

blue  and  violet,  59 
Kuphaniline,  27 

LAURENT  and  Hofmann's  me- 
thod of  producing  aniline,  13 
Lauth's  process  for  preparing  aniline 
black,  86 

 blue,  59 

Lead,  nitrate  of,  37 

—  picrate  of,  90 


l62 


INDEX. 


Leukaniline,  51,  120 

—  brown  from,  93 

—  composition  and  properties  of,  51 

—  hydrochlorates  of,  51 

—  nitrate  of,  52 
Leukoline,  12 

Levinstein's  process  for  preparing 
aniline  blue,  62 

Light  hydrocarbons,  2 

Lightfoot's  process  for  preparing 
aniline  black,  85 

Lowe,  Calvert,  and  Clift's  pro- 
cess for  preparing  emeraldine,  76 

Lucius's  process  for  preparing  aniline 
green,  81 

MAGENTA,  33 
—  apparatus  used  for  prepar- 
ing, 39 

—  arsenic  acid  used  for  preparing,  39, 

—  Blackley's  process  for  preparing, 

—  Brooman's  process  for  preparing, 

35 

—  crystals,  44 

—  Dale  and  Caro's  process  for  pre- 

paring, 37 

—  Delvaux's  process  for  preparing, 

47  ,  T 

—  Depouilly  and  Lauth's  process 

for  preparing,  38 

—  Fol's  process  for  preparing,  46 

—  Geber-Keller's  process  for  pre- 

paring, 36 

—  Girard  and  de  Laire's  process 

for  preparing,  39 

—  Gratrix's  process  for  preparing, 

45 

—  Hofmann's  process  for  preparing, 

34 

 researches  on,  48 

—  Hughes's  process  for  preparing, 

38 

—  kind  of  aniline  oil  for  manufactur- 

ing, 30,  33 

—  Kozchlin's  process  for  preparing, 

46 

—  Medlock's  process  for  preparing, 

39>  114 

—  Mounet  and  Dury's  process  for 

preparing,  34 

—  N at ansan's  process  for  preparing, 

35 

—  Perkin's  process  for  preparing,  36 

—  Renard  and  Franc's  process  for 

preparing,  35 

—  Schlumberger's  process  for  pre- 

paring, 36 

—  Smith's  process  for  preparing,  45, 

47 

—  theoretical  observations  on,  47 


Magenta,  Watson's  process  for  pre- 
paring, 38 

—  Williams's  process  for  preparing, 

37 

Mansfield's  apparatus  for  distilla- 
tion of  benzol,  107 

Maroon,  aniline,  137 

Martin's  process  for  preparing  ani- 
line yellow,  91 

Mauvaniline,  121 

Mauveine,  68,  137 

—  carbonate  of,  69 

—  hydrochlorate  of,  6g 

—  blue,  137 

—  grey,  137 

Medlock's  process  for  preparing  ma- 
genta, 39,  114 
Mercury,  nitrate  of,  36,  123 
Methyl,   preparation  of   iodide  of, 
73 

Methylation,  violet  produced  by,  129 

Methylrosaniline,  131 

Mirbane,  essence  of,  6,  7 

Mono-phenyl-rosaniline,  68 

Mounet  and  Dury's  process  for  pre- 
paring magenta,  34 

Muller  and  Co's  process  for  prepar- 
ing aniline  green,  78 

NAPHTHALIN,  3,  4,  12 
—  derivatives  of,  149 

—  distillation  of,  5 
Naphthyl,  3 
Naphthylamine,  149 

—  yellow,  149 
Naphthylated  hydrogen,  3 
Natanson's  process  for  preparing 

magenta,  35 
Newcastle  coal,  tar  of,  4 
Nicholson's  researches  on  aniline 

blue  and  violet,  66 

 chrysaniline,  53 

 magenta,  48,  50 

Night  blue,  61,  127 
Nitraniline,  11,  21 
Nitrate  of  aniline,  21 

 chrysaniline,  54 

 lead,  37 

 leukaniline,  52 

 mercury,  36,  123 

Nitric  acid,  8 
Nitrobenzol,  6,  14 

—  manufacture  of,  7,  9,  108 
Nitronaphthalin,  149 
Nitro-cumol,  7 
Nitro-cymol,  7 
Nitro-toluol,  7 

ODORINE,  properties  of,  24 
Oil  of  bitter  almonds,  6 

—  photogen,  3 

—  solar,  3 


INDEX. 


Orange,  Vi&oria,  90 
Oxalate  of  aniline,  20 

 rosaniline,  50 

 toluidine,  22 

Oxide  of  phenyl,  2 

PARAFFIN,  4 
Paranaphthalin,  12 
Paraniline,  25 

Passavant's  process  for  preparing 

aniline  blue,  61 
Peonine,  148 

Perkin's  process  for  preparing  ma- 
genta, 36 
 aniline  violet,  76 

—  violet,  68 

Perkin  and  Church's  process  for 
preparing  aniline  violet,  55 

Persoz,  de  Luynes,  and  Salvetat's 
process  for  preparing  aniline 
blue,  58 

Phenic  acid,  2,  4,  12,  144 

Phenate  of  ammonia,  12 

Phenyl,  1,  18 

—  hydrate  of  oxide  of,  2 

—  hydrogen  compound  of,  2,  6 
Phenylamide,  13 
Phenylamine,  13,  18,  74 
Phenylated  hydrogen,  1 
Phenylation,  blue  and  violet  colours 

obtained  by,  123 
Phenylic  violets,  128 
Phenyltotylamine,  in 
Phenylrosaniline,  75 
Phillips's    process    for  preparing 

aniline  violet,  57 
Phthalic  acid,  150 
Photogen  oil,  3 
Picoline,  12 
Picramic  acid,  147 
Picrate  of  lead,  go 

 rosaniline,  51 

Picric  acid,  78,  145 

 derivatives  of,  146 

 yellow,  89 

Potash,  isatate  of,  13 

Price's  process  for  preparing  aniline 

blue  and  violet,  60 

 violet,  58 

Primula,  71 

Purple,  aniline,  Crossley's  process 

for  preparing,  57 
Pyrrhol,  12 

RED,  aniline,  33 
Renard  and  Franc's  process 
for  preparing  magenta,  35 
Report  on  the  coal-tar  colours  shown 
at  the  French  Exhibition,  1867, 
99 

Rosaniline,  41,  112,  117 

—  acetate  of,  48,  50,  118 


Rosaniline,  arseniate  of,  42 

—  chromate  of,  51 

—  composition  and  properties  of,  49 

—  formiate  of,  51 

—  hydrobromate  of,  50 

—  hydrochlorates  of,  49,  116 

—  oxalate  of,  50 

—  picrate  of,  51 

—  sulphate  of,  50 
Rosolic  acid,  147 
Rubine,  36,  123 

Runge,  M.,  discovered  pyrrhol,  ani- 
line, and  leukoline,  12 

SCARLET,  aniline,  91 
Schaffer  and  Gros-Renard's 
process   for  preparing  aniline 
blue,  58 

Schlumberger's  process  for  prepar- 
ing aniline  blue,  61 

 magenta,  36 

Smith's  process  for  preparing  ma- 
genta, 45,  47 

Soap  used  in  making  aniline  blue  and 
violet,  65 

Solar  oil,  3 

Stadeler's  process   for  preparing 

aniline  violet,  58 
Staffordshire  coal,  tar  of,  4 
Steam,  distillation  of  benzol  by  means 

of,  4 

Sulphate  of  aniline,  13,  19,  20 

 chinoline,  24 

 chrysaniline,  54 

 rosaniline,  50 

 toluidine,  22 

Sulpho-triphenylrosanilic  acid,  128 
Sulphuric  acid,  8 

TAR,  dry,  4 
Tar  of  boghead,  Cannel,  New- 
castle, and  Staffordshire  coals,  4 
Tin,  bichloride  of,  35 
Tinctorial   power  and   intensity  of 
aniline   colours,  determination 
of,  95 
Toluidine,  ig,  21 

—  blue,  75 

—  hydrochlorate  of,  22 

—  oxalate  of,  22 

—  properties  of,  22 

—  sulphate  of,  22 
Toluol,  2,  4,  18,  106 
Tolyl,  18 

—  hydrogen  compound  of,  2,  6 
Triethylrosaniline,  70 
Trimethylrosaniline,  73 
Trinitrophenic  acid,  89 
Triphenylleukaniline,  69 
Triphenylrosaniline,  67,  123 
Tritolylrosaniline,  75,  123 
Turpentine,  oil  of,  76 


164 


INDEX. 


UNVERDORBEN,  M.,  discovered 
aniline,  13 
Usebe's  process  for  preparing  aniline 
green,  82 

VICTORIA  orange,  90 
Violaniline,  121 
Violet,  aniline,  55,  123 

 Beale  and  Kirkham's  process 

for  preparing,  57 

 Dale  and  Caro's  process  for 

preparing,  58 

 Gilbee's  process  for  preparing, 

61 

 Girard  and  de  Laire's  pro- 
cess for  preparing,  5g 

 Kopp's  process  for  preparing, 

59 

 Perkin  and  Church's  process 

for  preparing,  55 

 Phillip's  process  for  pre- 
paring, 57 

 Price's  process  for  preparing, 

58 

 Williams's  process  for  pre- 
paring, 58 

 Wilm's  process  for  preparing, 

56 

—  Hofmann's,  70 

—  de  Mtrihouse,  59 

—  and    blue,   aniline,  manufacture 

of,  on  a  large  scale,  63 

—  Perkin's,  68 
Violets,  phenylic,  128 


Violets    produced    by  methylation, 
ethylation,  and  phenylation,  129 
Viridine,  81 

Vogel's  process  for  preparing  aniline 
yellow,  90 

WATER,  ammoniacal,  2 
Watson's  process  for  prepar- 
ing magenta,  38 
Williams's  process  for  preparing 
aniline  blue,  63 

 and  violet,  58 

 magenta,  37 

Wilm's  process  for  preparing  aniline 

green,  76 
 violet,  56 

XYLIDINE,  19 
Xylol,  18 
Xylyl,  18 

YELLOW,  aniline,  89,  120 
 Crossley's  process  for 

preparing,  57 

 Martin's  process  for  preparing, 

91 

 Vogel's  process  for  preparing, 

90 

—  naphthylamine,  149 

ZINALINE,  91 
Zinc  powder,  used  in  manuiac- 
ture  of  aniline,  17 


Printed  by  William  Crookes,  at  the  Chemical  News  Office,  Boy  Court,  Ludgate  Hill,  E.C. 


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